[PATCH 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in debugfs, through which users can check
whether the debug capability is supported by a specific host controller.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.

Lu Baolu (12):
  usb: xhci: expose xhci extended capabilities via debugfs
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: xhci: dbc: probe and setup xhci debug capability
  usb: xhci: dbc: add support for Intel xHCI dbc quirk
  usb: xhci: dbc: add debug buffer
  usb: xhci: dbc: add bulk out and bulk in interfaces
  usb: xhci: dbc: handle dbc-configured exit
  usb: xhci: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: xhci: dbc: add handshake between debug target and host
  usb: serial: usb_debug: add support for dbc debug device
  usb: doc: add document for xHCI DbC driver

 Documentation/kernel-parameters.txt |1 +
 Documentation/usb/xhci-dbc.txt  |  325 
 MAINTAINERS |8 +
 arch/x86/Kconfig.debug  |   12 +
 arch/x86/include/asm/fixmap.h   |4 +
 arch/x86/kernel/early_printk.c  |5 +
 drivers/usb/early/Makefile  |1 +
 drivers/usb/early/xhci-dbc.c| 1407 +++
 drivers/usb/host/xhci-dbg.c |  212 ++
 drivers/usb/host/xhci-ext-caps.h|9 +-
 drivers/usb/host/xhci.c |   27 +-
 drivers/usb/host/xhci.h |   10 +
 drivers/usb/serial/usb_debug.c  |   29 +-
 include/linux/usb/xhci-dbc.h|  224 ++
 14 files changed, 2269 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

-- 
2.1.4

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[PATCH 02/12] x86: fixmap: add permanent fixmap for xhci debug port

[Lu Baolu]

xHCI compatible USB3 host controller may provide debug capability
which enables low-level system debug over USB. In order to probing
this debug capability, Linux kernel needs to map and access the
mmio of the host controller during early boot.

This patch adds permenent fixmap pages in fixed_addresses table for
xHCI mmio access.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 arch/x86/include/asm/fixmap.h | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index f80d700..fbf452f 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -82,6 +82,10 @@ enum fixed_addresses {
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
FIX_OHCI1394_BASE,
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   FIX_XDBC_BASE,
+   FIX_XDBC_END = FIX_XDBC_BASE + 15,
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
 #endif
-- 
2.1.4

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Re: [PATCH 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu, Baolu]

On 10/28/2015 05:10 PM, Johan Hovold wrote:

On Wed, Oct 28, 2015 at 04:00:42PM +0800, Lu Baolu wrote:

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  drivers/usb/serial/usb_debug.c | 29 ++---
  1 file changed, 26 insertions(+), 3 deletions(-)
  

+static struct usb_serial_driver dbc_device = {
+   .driver = {
+   .owner =THIS_MODULE,
+   .name = "xhci_dbc",
+   },
+   .id_table = dbc_id_table,
+   .num_ports =1,
+   .bulk_out_size =1024,

No need to set this unless you need a larger (or smaller for ehci)
buffer than the endpoint size.


I will remove it in v2. Thanks for pointing this out.



Johan



Thanks,
Baolu
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[PATCH v2 1/1] usb: xhci: fix checking ep busy for CFC

[Lu Baolu]

Function ep_ring_is_processing() checks the dequeue pointer
in endpoint context to know whether an endpoint is busy with
processing TRBs. This is not correct since dequeue pointer
field in an endpoint context is only valid when the endpoint
is in Halted or Stopped states. This buggy code causes audio
noise when playing sound with USB headset connected to host
controllers which support CFC (one of xhci 1.1 features).

This patch should exist in stable kernel since v4.3.

Reported-and-tested-by: YD Tseng <yd_ts...@asmedia.com.tw>
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>

---
v1->v2:
Implement the logic in xhci_queue_isoc_tx_prepare() instead of
a seperated function as suggested by Mathias.

---
 drivers/usb/host/xhci-ring.c | 32 ++--
 1 file changed, 6 insertions(+), 26 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fa83625..8edc286 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3896,28 +3896,6 @@ cleanup:
return ret;
 }
 
-static int ep_ring_is_processing(struct xhci_hcd *xhci,
-   int slot_id, unsigned int ep_index)
-{
-   struct xhci_virt_device *xdev;
-   struct xhci_ring *ep_ring;
-   struct xhci_ep_ctx *ep_ctx;
-   struct xhci_virt_ep *xep;
-   dma_addr_t hw_deq;
-
-   xdev = xhci->devs[slot_id];
-   xep = >devs[slot_id]->eps[ep_index];
-   ep_ring = xep->ring;
-   ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);
-
-   if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) != EP_STATE_RUNNING)
-   return 0;
-
-   hw_deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
-   return (hw_deq !=
-   xhci_trb_virt_to_dma(ep_ring->enq_seg, ep_ring->enqueue));
-}
-
 /*
  * Check transfer ring to guarantee there is enough room for the urb.
  * Update ISO URB start_frame and interval.
@@ -3983,10 +3961,12 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, 
gfp_t mem_flags,
}
 
/* Calculate the start frame and put it in urb->start_frame. */
-   if (HCC_CFC(xhci->hcc_params) &&
-   ep_ring_is_processing(xhci, slot_id, ep_index)) {
-   urb->start_frame = xep->next_frame_id;
-   goto skip_start_over;
+   if (HCC_CFC(xhci->hcc_params)) {
+   if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK)
+   == EP_STATE_RUNNING &&
+   !list_empty(_ring->td_list))
+   urb->start_frame = xep->next_frame_id;
+   goto skip_start_over;
}
 
start_frame = readl(>run_regs->microframe_index);
-- 
2.1.4

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Re: [PATCH 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu, Baolu]

On 10/28/2015 08:33 PM, Greg Kroah-Hartman wrote:

On Wed, Oct 28, 2015 at 04:00:42PM +0800, Lu Baolu wrote:

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  drivers/usb/serial/usb_debug.c | 29 ++---
  1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..d4903b0 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
  };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);

You shouldn't need a "combined" module device table anymore, the module
core was changed a while ago to remove that restriction, you should be
able to just multiple exports of MODULE_DEVICE_TABLE and everything
should "just work" on the export side.  Now it might not work on the usb
core side, but that's a different issue...


Thanks for pointing this out. I will re-factor this code in v2 patch.



thanks,

greg k-h



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Re: [PATCH 1/1] usb: xhci: fix checking ep busy for CFC

[Lu, Baolu]

On 10/28/2015 09:27 PM, Mathias Nyman wrote:

On 28.10.2015 03:36, Lu Baolu wrote:

Function ep_ring_is_processing() checks the dequeue pointer
in endpoint context to know whether an endpoint is busy with
processing TRBs. This is not correct since dequeue pointer
field in an endpoint context is only valid when the endpoint
is in Halted or Stopped states. This buggy code causes audio
noise when playing sound with USB headset connected to host
controllers which support CFC (one of xhci 1.1 features).

This patch should exist in stable kernel since v4.3.

Reported-and-tested-by: YD Tseng <yd_ts...@asmedia.com.tw>
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  drivers/usb/host/xhci-ring.c | 5 +
  1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fa83625..2b50d45 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3903,7 +3903,6 @@ static int ep_ring_is_processing(struct 
xhci_hcd *xhci,

  struct xhci_ring *ep_ring;
  struct xhci_ep_ctx *ep_ctx;
  struct xhci_virt_ep *xep;
-dma_addr_t hw_deq;

  xdev = xhci->devs[slot_id];
  xep = >devs[slot_id]->eps[ep_index];
@@ -3913,9 +3912,7 @@ static int ep_ring_is_processing(struct 
xhci_hcd *xhci,
  if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) != 
EP_STATE_RUNNING)

  return 0;

-hw_deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
-return (hw_deq !=
-xhci_trb_virt_to_dma(ep_ring->enq_seg, ep_ring->enqueue));
+return !list_empty(_ring->td_list);
  }


Would it make sense to remove the ep_ring_is_processing() function 
completely?


It is only called in one place, and the main use is checking 
list_empty(_ring->td_list).

This could be checked directly in xhci_queue_isoc_tx_prepare()


Fair enough. I will make this change and send out the v2.



-Mathias


Thanks,
Baolu



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Re: [PATCH 01/12] usb: xhci: expose xhci extended capabilities via debugfs

[Lu, Baolu]

On 10/28/2015 05:27 PM, Oliver Neukum wrote:

+static int fill_buffer(struct debug_buffer *buf)
>+{
>+   int ret;
>+
>+   if (buf->output_buf)
>+   return -EINVAL;
>+
>+   buf->alloc_size = PAGE_SIZE;
>+   buf->output_buf = vmalloc(buf->alloc_size);

That really makes no sense. If you allocate exactly
PAGE_SIZE, you should allocate a page.


Yes, I will change it in v2.



Regards
Oliver


Thanks,
Baolu







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Re: [PATCH 01/12] usb: xhci: expose xhci extended capabilities via debugfs

[Lu, Baolu]

On 10/28/2015 08:40 PM, Greg Kroah-Hartman wrote:

>+struct debug_buffer {
>+   ssize_t (*fill_func)(struct debug_buffer *);
>+   struct usb_bus *bus;
>+   struct mutex mutex;
>+   size_t count;
>+   char *output_buf;
>+   size_t alloc_size;
>+};
>+
>+static const char *get_extcap_desc(u32 cap_id)
>+{
>+   switch (cap_id) {
>+   case XHCI_EXT_CAPS_LEGACY:
>+   return "USB Legacy Support";
>+   case XHCI_EXT_CAPS_PROTOCOL:
>+   return "Supported Protocol";
>+   case XHCI_EXT_CAPS_PM:
>+   return "Extended Power Management";
>+   case XHCI_EXT_CAPS_VIRT:
>+   return "I/O Virtualization (xHCI-IOV)";
>+   case XHCI_EXT_CAPS_ROUTE:
>+   return "Message Interrupt";
>+   case XHCI_EXT_CAPS_LOCALMEM:
>+   return "Local Memory";
>+   case XHCI_EXT_CAPS_DEBUG:
>+   return "USB Debug Capability";

This is a lot more stuff than just debug port, it should be in sysfs
as individual files, not one big one that you somehow have to parse in
order to determine this information.



I will move it into sysfs in v2.

Thanks,
Baolu
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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

On 11/07/2015 07:05 PM, Steinar H. Gunderson wrote:

Can you cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u1
>and /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u2 for several
>times? Don't use that device when cat these two files.

I waited a bit longer, and indeed, now it consistently shows enabled on both
cards.

   klump:~> cat /sys/bus/usb/devices/2-1/power/usb3_hardware_lpm_u1
   enabled
   klump:~> cat /sys/bus/usb/devices/2-1/power/usb3_hardware_lpm_u2
   enabled
   klump:~> cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u1
   enabled
   klump:~> cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u2
   enabled


That's good. Thank you for your time.

We've got below facts:

1. One card works well w/ or w/o LPM enabled.
2. Two cards work well w/o LPM, but not work w/ LPM. The error
is "not enough bus bandwidth".

We can come to a conclusion that "LPM consumes extra usb bus
bandwidth, this extra bandwidth could cause device not to work
due to limited bandwidth resources."

I have a patch attached in this email. It can disable LPM for any
devices during run time. Do you mind having a try? You can follow
below steps:

1) apply the attached two patches on top of the latest 4.3 kernel.
0001-usb-core-lpm-fix-usb3_hardware_lpm-sysfs-node.patch
0002-usb-core-lpm-add-sysfs-node-for-usb3-lpm-permit.patch
2) build and install the kernel.
3) boot your machine with the new kernel.
4) insert two  Blackmagic Design device into USB3 root port.
5) disable LPM for devices in step 4).

# echo "0" > /sys/bus/usb/devices/<1st_device_path>/port/usb3_lpm_permit
# echo "0" > /sys/bus/usb/devices/<2nd_device_path>/port/usb3_lpm_permit

You can check your setting by reading the sysfs file. They should read 0.

6) start the two devices at the same time, can they work at the same time?

Thanks,
Baolu


For fun, I tried also with a USB 2.0 cable. U1 and U2 comes up as disabled,
but of course, the device doesn't work.

/* Steinar */


>From 836c0ab187bcc5a08ac3a6d55136203f922ad95b Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu...@linux.intel.com>
Date: Fri, 6 Nov 2015 09:53:59 +0800
Subject: [PATCH 2/3] usb: core: lpm: add sysfs node for usb3 lpm permit

USB3 LPM is default on in Linux kernel if both xHCI host controller
and the USB devices declare to be LPM-capable. Unfortunately, some
devices are known to work well with LPM disabled, but to be broken
if LPM is enabled, although it declares the LPM capability.  Users
won't be able to use this kind of devices, until someone puts them
in the kernel blacklist and gets the kernel upgraded.

This patch adds a sysfs node to permit or forbit USB3 LPM U1 or U2
entry for a port. The settings apply to both before and after device
enumeration. Supported values are "0" - neither u1 nor u2 permitted,
"u1" - only u1 is permitted, "u2" - only u2 is permitted, "u1_u2" -
both u1 and u2 are permitted.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Zhuang Jin Can <jin.can.zhu...@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 11 
 drivers/usb/core/hub.c  | 15 +-
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 4 files changed, 116 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 136ba17..4165c37 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -189,6 +189,17 @@ Description:
 		The file will read "hotplug", "wired" and "not used" if the
 		information is available, and "unknown" otherwise.
 
+What:		/sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
+Date:		November 2015
+Contact:	Lu Baolu <baolu...@linux.intel.com>
+Description:
+		Some USB3.0 devices may not support usb3 lpm well. usb3_lpm_permit
+		attribute allows enabling/disabling usb3 lpm of a port. It takes
+		effect both before and after a usb device is enumerated. Supported
+		values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1
+		is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
+		u2 are permitted.
+
 What:		/sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:		May 2013
 Contact:	Mathias Nyman <mathias.ny...@linux.intel.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 94a10e0..023e39f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4012,6 +4012,8 @@ EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);
 void usb_enable_lpm(struct usb_device *udev)
 {
 	struct usb_hcd *hcd;
+	struct usb_hub *hub;
+	struct usb_port *port_dev;
 
 	if (!udev || !udev->parent ||
 			udev->speed != USB_SPEED_SUPER ||
@@ -4031,8 +4033,17 @

[PATCH v3 02/12] x86: fixmap: add permanent fixmap for xhci debug port

[Lu Baolu]

xHCI compatible USB3 host controller may provide debug capability
which enables low-level system debug over USB. In order to probing
this debug capability, Linux kernel needs to map and access the
mmio of the host controller during early boot.

This patch adds permenent fixmap pages in fixed_addresses table for
xHCI mmio access.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 arch/x86/include/asm/fixmap.h | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index f80d700..fbf452f 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -82,6 +82,10 @@ enum fixed_addresses {
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
FIX_OHCI1394_BASE,
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   FIX_XDBC_BASE,
+   FIX_XDBC_END = FIX_XDBC_BASE + 15,
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
 #endif
-- 
2.1.4

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[PATCH v3 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu Baolu]

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Acked-by: Johan Hovold <jo...@kernel.org>
---
 drivers/usb/serial/usb_debug.c | 28 +---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..92f7e5c 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
 };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);
 
 /* This HW really does not support a serial break, so one will be
  * emulated when ever the break state is set to true.
@@ -71,9 +82,20 @@ static struct usb_serial_driver debug_device = {
.process_read_urb = usb_debug_process_read_urb,
 };
 
+static struct usb_serial_driver dbc_device = {
+   .driver = {
+   .owner =THIS_MODULE,
+   .name = "xhci_dbc",
+   },
+   .id_table = dbc_id_table,
+   .num_ports =1,
+   .break_ctl =usb_debug_break_ctl,
+   .process_read_urb = usb_debug_process_read_urb,
+};
+
 static struct usb_serial_driver * const serial_drivers[] = {
-   _device, NULL
+   _device, _device, NULL
 };
 
-module_usb_serial_driver(serial_drivers, id_table);
+module_usb_serial_driver(serial_drivers, id_table_combined);
 MODULE_LICENSE("GPL");
-- 
2.1.4

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[PATCH v3 12/12] usb: doc: add document for xHCI DbC driver

[Lu Baolu]

Add Documentation/usb/xhci-dbc.txt. This document includes
development status and user guide for USB3 debug port.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/usb/xhci-dbc.txt | 325 +
 MAINTAINERS|   1 +
 drivers/usb/early/xhci-dbc.c   |   3 +
 3 files changed, 329 insertions(+)
 create mode 100644 Documentation/usb/xhci-dbc.txt

diff --git a/Documentation/usb/xhci-dbc.txt b/Documentation/usb/xhci-dbc.txt
new file mode 100644
index 000..441b40c
--- /dev/null
+++ b/Documentation/usb/xhci-dbc.txt
@@ -0,0 +1,325 @@
+xHCI debug capability driver
+
+         Lu Baolu <baolu...@linux.intel.com>
+
+Last-updated: September 2015
+
+
+   Contents:
+   -
+   * What is xHCI DbC?
+   * Debug topologies
+   * Debug stacks
+   * Port Multiplexing
+   * Hardware initialization
+   * External reset
+   * Port reset
+   * Interrupt/DMA/Memory during early boot
+   * Endpoint STALL
+   * Debug device information
+   * How to use DbC early printk?
+   * Limitations
+
+   What is xHCI DbC?
+   -
+
+The xHCI Debugging Capability defined in section 7.6 of xHCI spec 1.1
+provides an optional functionality that enables low-level system debug
+over USB. It provides a means of connecting two systems where one system
+is a Debug Host and the other a Debug Target (System Under Test). The
+Debug Capability provides an interface that is completely independent
+of the xHCI interface. A Debug Target enumerates as a USB debug device
+to the Debug Host, allowing a Debug Host to access a Debug Target through
+the standard USB software stack.
+
+   Debug topologies
+   
+
+Multiple Debug Targets may be attached to a single Debug Host. Debug
+Targets may be connected to any downstream facing port below a Debug
+Host (i.e. anywhere in the fabric, root port or external hub puts).
+A Debug Target may only connect to a Debug Host through a Root Hub port
+of the target. That means connection of a Debug Target to a Debug Host
+through the ports of an external hub is not supported.
+
+Below is a typical connection between Debug Host and Debug target. Two
+Debug targets are connected to a single Debug host.
+
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+  || |
+  ||_|
+  |_
+|
+ ___|
+|   HUB  |  |  Debug Target  |
+||  ||
+| Superspeed hub |  |  xHC with DbC  |
+||  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+   Debug stacks
+   
+
+Below is a software stack diagram of both Debug Host and Debug Target.
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|   debug App|  ||
+||  | system debug   |
+|   usb_debug|  | hooks  |
+||  ||
+|usbcore |  ||
+||  |debug capability|
+|xhci_hcd|  | driver |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+
+   Port Multiplexing
+   -
+
+A debug port is always multiplexed with the first xHCI root hub port.
+Whenever debug capability is supported and enabled, and the first root
+hub port is detected to be connected to a downstream super-speed port
+of a Debug Host, the r

Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

Hi Dave,

Which device are you testing with? This implementation was developed
and tested on Intel Skylake devices.

It doesn't surprise me if it doesn't work with other silicons. But it do
remind me to create a verified-list and put those known-to-work devices
in it.

Thanks,
Baolu

On 11/11/2015 10:25 AM, Dave Young wrote:

Hi,

On 11/11/15 at 09:32am, Lu, Baolu wrote:


On 11/10/2015 05:39 PM, Dave Young wrote:

Hi,

On 11/09/15 at 03:38pm, Lu Baolu wrote:

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.


I did a test with your previous patchset with the manually wired cable.
debug host detected the remote device, but later the devie automaticlly
disconnected and earlyprintk hangs.

Hi Dave,

What I have done is:

Retested it, seems it is not stable. I got a sucessful boot with earlyprintk
But only once and there was no "Press Y to continue", I just blindly pressed Y.

The other tests failed.

Since it is not convinience to test, do you have way to enable the dbc
after kernel boot? like echo 1 to a sysfs file to enable it.

(1) Build a new kernel for debug target with this patch series applied.
(2) Add "earlyprintk=xdbc" to the kernel option of debug target. The
  "keep" option for early printk doesn't support yet. (That's my next
  target.)

(3) Boot the debug host, and disable USB runtime suspend:

# echo on > /sys/bus/pci/devices//power/control
# echo on | tee /sys/bus/usb/devices/*/power/control

(4) Boot the debug target. Check the dmesg message on debug host.

# tail -f /var/log/kern.log

Nov 12 01:27:50 allen-ult kernel: [ 1815.983374] usb 4-3: new SuperSpeed USB
device number 4 using xhci_hcd
Nov 12 01:27:50 allen-ult kernel: [ 1815.999595] usb 4-3: LPM exit latency
is zeroed, disabling LPM.
Nov 12 01:27:50 allen-ult kernel: [ 1815.999899] usb 4-3: New USB device
found, idVendor=1d6b, idProduct=0004
Nov 12 01:27:50 allen-ult kernel: [ 1815.02] usb 4-3: New USB device
strings: Mfr=1, Product=2, SerialNumber=3
Nov 12 01:27:50 allen-ult kernel: [ 1815.03] usb 4-3: Product: Remote
GDB
Nov 12 01:27:50 allen-ult kernel: [ 1815.04] usb 4-3: Manufacturer:
Linux
Nov 12 01:27:50 allen-ult kernel: [ 1815.05] usb 4-3: SerialNumber: 0001
Nov 12 01:27:50 allen-ult kernel: [ 1816.000240] usb_debug 4-3:1.0: xhci_dbc
converter detected
Nov 12 01:27:50 allen-ult kernel: [ 1816.000360] usb 4-3: xhci_dbc converter
now attached to ttyUSB0

(5) Host has completed enumeration of debug device. Start "minicom" on debug
host.


Most times I have no chance to run minicom before the usb disconnection here.


Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Jan  1 2014, 17:13:19.
Port /dev/ttyUSB0, 01:28:02

Press CTRL-A Z for help on special keys

Press Y to continue...

(6) You should be able to see "Press Y to continue..." (if not, try pressing
Enter key)
Press Y key, debug target should go ahead with boot and early boot messages
should show in mincom.

Press Y to continue...
[0.00] Initializing cgroup subsys cpuset
[0.00] Initializing cgroup subsys cpu
[0.00] Initializing cgroup subsys cpuacct
[0.00] Linux version 4.3.0-rc7+ (allen@blu-skl) (gcc version 4.8.4
(Ubuntu 4.8.4-2ubuntu1~14.04) 5
[0.00] Command line: BOOT_IMAGE=/boot/vmlinuz-4.3.0-rc7+
root=UUID=5a2fb856-0238-4b6e-aa45-beeccb7
[0.00] KERNEL supported cpus:

[...skipped...]

[0.00]  Offload RCU callbacks from CPUs: 0-7.
[0.00] Console: colour dummy device 80x25
[0.00] console [tty0] enabled
[0.00] bootconsole [earlyxdbc0] disabled


So "the devie automaticlly disconnected and earlyprintk hangs" happens in
which step?


Here is some log on host side.

[ 1568.052135] usb 2-2: new SuperSpeed USB device number 5 using xhci_hcd
[ 1568.063416] usb 2-2: LPM exit latency is zeroed, disabling LPM.
[ 1568.063750] usb 2-2: New USB device found, idVendor=1d6b, idProduct=0004
[ 1568.063751] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1568.063752] usb 2-2: Product: Remote GDB
[ 1568.063753] usb 2-2: Manufacturer: Linux
[ 1568.063754] usb 2-2: SerialNumber: 0001
[ 1568.065580] usb_debug 2-2:1.0: xhci_dbc converter detected
[ 1568.066309] usb 2-2: xhci_dbc converter now attached to ttyUSB0
[ 1580.464706] usb 2-2: USB disconnect, device number 5
[ 1580.464996] xhci_dbc ttyUSB0: xhci_dbc converter now disconnected from 
ttyUSB0
[ 1580.465062] usb_debug 2-2:1.0: device disconnected
[ 1580.670743] usb 2-2: new SuperSpeed USB device number 6 using xhci_hcd
[ 1580.682068] usb 2-2: LPM exit latency is zeroed, disabling LPM.
[ 1580.682667] usb 2-2: New USB device found, idVendor=1d6b, idProduct=0004
[ 1580.682672] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1580.682675] usb 2-2: Product: Remote GDB
[ 1580.682678] usb 2-2: Manufacturer: Linux
[ 1580.68268

[PATCH v2 2/3] usb: core: lpm: add sysfs node for usb3 lpm permit

[Lu Baolu]

USB3 LPM is default on in Linux kernel if both xHCI host controller
and the USB devices declare to be LPM-capable. Unfortunately, some
devices are known to work well with LPM disabled, but to be broken
if LPM is enabled, although it declares the LPM capability.  Users
won't be able to use this kind of devices, until someone puts them
in the kernel blacklist and gets the kernel upgraded.

This patch adds a sysfs node to permit or forbit USB3 LPM U1 or U2
entry for a port. The settings apply to both before and after device
enumeration. Supported values are "0" - neither u1 nor u2 permitted,
"u1" - only u1 is permitted, "u2" - only u2 is permitted, "u1_u2" -
both u1 and u2 are permitted. With this interface, users can use an
LPM-unfriendly USB device on a released Linux kernel.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Zhuang Jin Can <jin.can.zhu...@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 11 
 drivers/usb/core/hub.c  | 15 +-
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 4 files changed, 116 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 136ba17..0bd731c 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -189,6 +189,17 @@ Description:
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
 
+What:  /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
+Date:  November 2015
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   Some USB3.0 devices are not friendly to USB3 LPM.  
usb3_lpm_permit
+   attribute allows enabling/disabling usb3 lpm of a port. It takes
+   effect both before and after a usb device is enumerated. 
Supported
+   values are "0" if both u1 and u2 are NOT permitted, "u1" if 
only u1
+   is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 
and
+   u2 are permitted.
+
 What:  /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:  May 2013
 Contact:   Mathias Nyman <mathias.ny...@linux.intel.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 4eb7369..9df568e 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4007,6 +4007,8 @@ EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);
 void usb_enable_lpm(struct usb_device *udev)
 {
struct usb_hcd *hcd;
+   struct usb_hub *hub;
+   struct usb_port *port_dev;
 
if (!udev || !udev->parent ||
udev->speed != USB_SPEED_SUPER ||
@@ -4026,8 +4028,17 @@ void usb_enable_lpm(struct usb_device *udev)
if (udev->lpm_disable_count > 0)
return;
 
-   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
-   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
+   hub = usb_hub_to_struct_hub(udev->parent);
+   if (!hub)
+   return;
+
+   port_dev = hub->ports[udev->portnum - 1];
+
+   if (port_dev->usb3_lpm_u1_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
+
+   if (port_dev->usb3_lpm_u2_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
 }
 EXPORT_SYMBOL_GPL(usb_enable_lpm);
 
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 688817f..45d070d 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -92,6 +92,8 @@ struct usb_hub {
  * @status_lock: synchronize port_event() vs usb_port_{suspend|resume}
  * @portnum: port index num based one
  * @is_superspeed cache super-speed status
+ * @usb3_lpm_u1_permit: whether USB3 U1 LPM is permitted.
+ * @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted.
  */
 struct usb_port {
struct usb_device *child;
@@ -104,6 +106,8 @@ struct usb_port {
struct mutex status_lock;
u8 portnum;
unsigned int is_superspeed:1;
+   unsigned int usb3_lpm_u1_permit:1;
+   unsigned int usb3_lpm_u2_permit:1;
 };
 
 #define to_usb_port(_dev) \
@@ -155,4 +159,3 @@ static inline int hub_port_debounce_be_stable(struct 
usb_hub *hub,
 {
return hub_port_debounce(hub, port1, false);
 }
-
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 2106183..cb18ce0 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -50,6 +50,72 @@ static ssize_t connect_type_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(connect_type);
 
+static ssize_t usb3_lpm_permit_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+   struct usb_port *port_dev = 

Re: [PATCH 3/3] usb: core: lpm: remove usb3_lpm_enabled in usb_device

[Lu, Baolu]

On 11/11/2015 11:10 PM, Alan Stern wrote:

On Wed, 11 Nov 2015, Lu Baolu wrote:


Commit 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.")
adds usb3_lpm_enabled member to struct usb_device. There is no reference
to this member now. Hence, it could be removed.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  include/linux/usb.h | 1 -
  1 file changed, 1 deletion(-)

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 211664f..036e4a5 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -583,7 +583,6 @@ struct usb_device {
unsigned usb2_hw_lpm_besl_capable:1;
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
-   unsigned usb3_lpm_enabled:1;
unsigned usb3_lpm_u1_enabled:1;
unsigned usb3_lpm_u2_enabled:1;
int string_langid;

You forgot to remove the kerneldoc for this field.  And you forgot to
add kerneldoc for usb3_lpm_u[12]_enabled.


Yes. I will fix this in v2.



Alan Stern


Thanks,
Baolu



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[PATCH v2 1/3] usb: core: lpm: fix usb3_hardware_lpm sysfs node

[Lu Baolu]

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: sta...@vger.kernel.org
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 16 +---
 Documentation/usb/power-management.txt  | 11 ++-
 drivers/usb/core/hub.c  | 20 ++--
 drivers/usb/core/sysfs.c| 31 ++-
 include/linux/usb.h |  4 
 5 files changed, 59 insertions(+), 23 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 3a4abfc..136ba17 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -134,19 +134,21 @@ Description:
enabled for the device. Developer can write y/Y/1 or n/N/0 to
the file to enable/disable the feature.
 
-What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm
-Date:  June 2015
+What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
+   /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
+Date:  November 2015
 Contact:   Kevin Strasser <kevin.stras...@linux.intel.com>
+   Lu Baolu <baolu...@linux.intel.com>
 Description:
If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
in to a xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS descriptor; if
-   the check is is passed and the host supports USB3 hardware LPM,
+   the check is passed and the host supports USB3 hardware LPM,
USB3 hardware LPM will be enabled for the device and the USB
-   device directory will contain a file named
-   power/usb3_hardware_lpm. The file holds a string value (enable
-   or disable) indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   device directory will contain two files named
+   power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
+   files hold a string value (enable or disable) indicating whether
+   or not USB3 hardware LPM U1 or U2 is enabled for the device.
 
 What:  /sys/bus/usb/devices/.../removable
 Date:  February 2012
diff --git a/Documentation/usb/power-management.txt 
b/Documentation/usb/power-management.txt
index 4a15c90..0a94ffe 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -537,17 +537,18 @@ relevant attribute files are usb2_hardware_lpm and 
usb3_hardware_lpm.
can write y/Y/1 or n/N/0 to the file to enable/disable
USB2 hardware LPM manually. This is for test purpose mainly.
 
-   power/usb3_hardware_lpm
+   power/usb3_hardware_lpm_u1
+   power/usb3_hardware_lpm_u2
 
When a USB 3.0 lpm-capable device is plugged in to a
xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS
descriptor; if the check is is passed and the host
supports USB3 hardware LPM, USB3 hardware LPM will be
-   enabled for the device and this file will be created.
-   The file holds a string value (enable or disable)
-   indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   enabled for the device and these files will be created.
+   The files hold a string value (enable or disable)
+   indicating whether or not USB3 hardware LPM U1 or U2
+   is enabled for the device.
 
USB Port Power Control
--
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bdeadc1..4eb7369 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,23 @@ static void usb_enable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
return;
}
 
-   if (usb_set_lpm_timeout(udev, state, timeout))
+   ret = usb_set_lpm_timeout(udev, state, timeout);
+   if (ret)
/* If we can't set the parent hub U1/U2 timeout,
 * device-initiated LPM won't be allowed either, so let the xHCI
 * host know that this link state won't be enabled.
 

[PATCH v2 0/3] usb: core: lpm: add sysfs node for usb3 lpm permit

[Lu Baolu]

Hi,

This patch series is about to add a sysfs attribute, through which
users can disable or enable USB3 LPM (link power management) from
a USB port. Once LPM is disabled from the USB port, LPM between the
downstreaming device and the hub port will not be activated. This
helps users to use any LPM-unfriendly USB devices on any released
Linux kernels.

This patch series contains a fix and a cleanup as well.

Change log:
v1->v2:
Fix the "make htmldoc" warning reported by 0-day robot.

Thanks,
Baolu

Lu Baolu (3):
  usb: core: lpm: fix usb3_hardware_lpm sysfs node
  usb: core: lpm: add sysfs node for usb3 lpm permit
  usb: core: lpm: remove usb3_lpm_enabled in usb_device

 Documentation/ABI/testing/sysfs-bus-usb | 27 +++---
 Documentation/usb/power-management.txt  | 11 ++--
 drivers/usb/core/hub.c  | 33 +---
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 drivers/usb/core/sysfs.c| 31 ++--
 include/linux/usb.h |  6 ++-
 7 files changed, 174 insertions(+), 28 deletions(-)

-- 
2.1.4

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[PATCH v2 3/3] usb: core: lpm: remove usb3_lpm_enabled in usb_device

[Lu Baolu]

Commit 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.")
adds usb3_lpm_enabled member to struct usb_device. There is no reference
to this member now. Hence, it could be removed.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 include/linux/usb.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/linux/usb.h b/include/linux/usb.h
index b79925d..89533ba 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -510,7 +510,6 @@ struct usb3_lpm_parameters {
  * @usb2_hw_lpm_besl_capable: device can perform USB2 hardware BESL LPM
  * @usb2_hw_lpm_enabled: USB2 hardware LPM is enabled
  * @usb2_hw_lpm_allowed: Userspace allows USB 2.0 LPM to be enabled
- * @usb3_lpm_enabled: USB3 hardware LPM enabled
  * @usb3_lpm_u1_enabled: USB3 hardware U1 LPM enabled
  * @usb3_lpm_u2_enabled: USB3 hardware U2 LPM enabled
  * @string_langid: language ID for strings
@@ -585,7 +584,6 @@ struct usb_device {
unsigned usb2_hw_lpm_besl_capable:1;
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
-   unsigned usb3_lpm_enabled:1;
unsigned usb3_lpm_u1_enabled:1;
unsigned usb3_lpm_u2_enabled:1;
int string_langid;
-- 
2.1.4

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Re: [PATCH v2 3/3] usb: core: lpm: remove usb3_lpm_enabled in usb_device

[Lu, Baolu]

On 11/13/2015 12:20 AM, Alan Stern wrote:

On Thu, 12 Nov 2015, Lu Baolu wrote:


Commit 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.")
adds usb3_lpm_enabled member to struct usb_device. There is no reference
to this member now. Hence, it could be removed.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>

Since patch 1/3 removes all the references to usb3_lpm_enabled, that
patch should also remove the member itself.  In other words, you might
as well fold this patch into that one.


I was thinking that 1/3 is a fix patch. It could be back ported to
various kernels. If I merged this patch with 1/3, it might cause
problems, i.e. usb3_lpm_enabled is still used in that kernel.

Thanks,
-baolu



Alan Stern




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Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

On 11/13/2015 10:26 AM, Dave Young wrote:

On 11/13/15 at 10:04am, Lu, Baolu wrote:

Hi Dave,

On 11/12/2015 02:01 PM, Dave Young wrote:

Hi, Baolu

On 11/12/15 at 10:45am, Lu, Baolu wrote:

Hi Dave,

Which device are you testing with? This implementation was developed
and tested on Intel Skylake devices.

It doesn't surprise me if it doesn't work with other silicons. But it do
remind me to create a verified-list and put those known-to-work devices
in it.


I have not got time to do more test. What infomation do you want?
lsusb -v?

lspci -v


Here is the controller information:

Host side:

00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family 
USB xHCI (rev 05) (prog-if 30 [XHCI])
Subsystem: Hewlett-Packard Company Device 1905
Flags: bus master, medium devsel, latency 0, IRQ 27
Memory at ef12 (64-bit, non-prefetchable) [size=64K]
Capabilities: 
Kernel driver in use: xhci_hcd

Target side:

00:14.0 USB controller: Intel Corporation 8 Series USB xHCI HC (rev 04) 
(prog-if 30 [XHCI])
Subsystem: Lenovo Device 220c
Flags: bus master, medium devsel, latency 0, IRQ 41
Memory at f062 (64-bit, non-prefetchable) [size=64K]
Capabilities: 
Kernel driver in use: xhci_hcd


Okay, thank you.

Thanks,
-Baolu


Thanks
Dave



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Re: [PATCH v2 1/3] usb: core: lpm: fix usb3_hardware_lpm sysfs node

[Lu, Baolu]

On 11/13/2015 12:20 AM, Alan Stern wrote:

On Thu, 12 Nov 2015, Lu Baolu wrote:


Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: sta...@vger.kernel.org
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>

...


--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,23 @@ static void usb_enable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
return;
}
  
-	if (usb_set_lpm_timeout(udev, state, timeout))

+   ret = usb_set_lpm_timeout(udev, state, timeout);
+   if (ret)
/* If we can't set the parent hub U1/U2 timeout,
 * device-initiated LPM won't be allowed either, so let the xHCI
 * host know that this link state won't be enabled.
 */
hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
-
/* Only a configured device will accept the Set Feature U1/U2_ENABLE */
else if (udev->actconfig)
usb_set_device_initiated_lpm(udev, state, true);
  
+	if (!ret) {

+   if (state == USB3_LPM_U1)
+   udev->usb3_lpm_u1_enabled = 1;
+   else if (state == USB3_LPM_U2)
+   udev->usb3_lpm_u2_enabled = 1;
+   }

This doesn't look right at all.  What happens if ret is 0 but the
device isn't configured?  You'll set the usb3_lpm_u*_enabled flag even
though LPM isn't really enabled.

Don't you want to set these flags inside the
usb_set_device_initiated_lpm() function, where you know whether the
action succeeded?  And leave this routine unchanged?


My understand is that both hub and device can initiate LPM.
As soon as usb_set_lpm_timeout(valid_timeout_value)
returns 0, the hub-initiated LPM is enabled. Thus, LPM is
enabled no matter the result of usb_set_device_initiated_lpm().
The only difference is whether device is able to initiate LPM.

On disable side, as soon as usb_set_lpm_timeout(0) return 0,
hub initiated LPM is disabled. Hub will disallows link to enter
U1/U2 as well, even device is initiating LPM. Hence LPM
is disabled as soon as hub LPM timeout set to 0, no matter
device-initiated LPM is disabled or not.

Thanks,
-Baolu




@@ -3925,6 +3931,12 @@ static int usb_disable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
dev_warn(>dev, "Could not disable xHCI %s timeout, "
"bus schedule bandwidth may be impacted.\n",
usb3_lpm_names[state]);
+
+   if (state == USB3_LPM_U1)
+   udev->usb3_lpm_u1_enabled = 0;
+   else if (state == USB3_LPM_U2)
+   udev->usb3_lpm_u2_enabled = 0;
+
return 0;
  }

And then this won't be necessary.

Alan Stern




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Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

Hi Dave,

On 11/12/2015 02:01 PM, Dave Young wrote:

Hi, Baolu

On 11/12/15 at 10:45am, Lu, Baolu wrote:

>Hi Dave,
>
>Which device are you testing with? This implementation was developed
>and tested on Intel Skylake devices.
>
>It doesn't surprise me if it doesn't work with other silicons. But it do
>remind me to create a verified-list and put those known-to-work devices
>in it.
>

I have not got time to do more test. What infomation do you want?
lsusb -v?


lspci -v

Thanks,
-Baolu





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[PATCH v3 2/3] usb: core: lpm: add sysfs node for usb3 lpm permit

[Lu Baolu]

USB3 LPM is default on in Linux kernel if both xHCI host controller
and the USB devices declare to be LPM-capable. Unfortunately, some
devices are known to work well with LPM disabled, but to be broken
if LPM is enabled, although it declares the LPM capability.  Users
won't be able to use this kind of devices, until someone puts them
in the kernel blacklist and gets the kernel upgraded.

This patch adds a sysfs node to permit or forbit USB3 LPM U1 or U2
entry for a port. The settings apply to both before and after device
enumeration. Supported values are "0" - neither u1 nor u2 permitted,
"u1" - only u1 is permitted, "u2" - only u2 is permitted, "u1_u2" -
both u1 and u2 are permitted. With this interface, users can use an
LPM-unfriendly USB device on a released Linux kernel.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Zhuang Jin Can <jin.can.zhu...@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 11 
 drivers/usb/core/hub.c  | 15 +-
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 4 files changed, 116 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 136ba17..0bd731c 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -189,6 +189,17 @@ Description:
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
 
+What:  /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
+Date:  November 2015
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   Some USB3.0 devices are not friendly to USB3 LPM.  
usb3_lpm_permit
+   attribute allows enabling/disabling usb3 lpm of a port. It takes
+   effect both before and after a usb device is enumerated. 
Supported
+   values are "0" if both u1 and u2 are NOT permitted, "u1" if 
only u1
+   is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 
and
+   u2 are permitted.
+
 What:  /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:  May 2013
 Contact:   Mathias Nyman <mathias.ny...@linux.intel.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 59f998e..db7683e 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4020,6 +4020,8 @@ EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);
 void usb_enable_lpm(struct usb_device *udev)
 {
struct usb_hcd *hcd;
+   struct usb_hub *hub;
+   struct usb_port *port_dev;
 
if (!udev || !udev->parent ||
udev->speed != USB_SPEED_SUPER ||
@@ -4039,8 +4041,17 @@ void usb_enable_lpm(struct usb_device *udev)
if (udev->lpm_disable_count > 0)
return;
 
-   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
-   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
+   hub = usb_hub_to_struct_hub(udev->parent);
+   if (!hub)
+   return;
+
+   port_dev = hub->ports[udev->portnum - 1];
+
+   if (port_dev->usb3_lpm_u1_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
+
+   if (port_dev->usb3_lpm_u2_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
 }
 EXPORT_SYMBOL_GPL(usb_enable_lpm);
 
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 688817f..45d070d 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -92,6 +92,8 @@ struct usb_hub {
  * @status_lock: synchronize port_event() vs usb_port_{suspend|resume}
  * @portnum: port index num based one
  * @is_superspeed cache super-speed status
+ * @usb3_lpm_u1_permit: whether USB3 U1 LPM is permitted.
+ * @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted.
  */
 struct usb_port {
struct usb_device *child;
@@ -104,6 +106,8 @@ struct usb_port {
struct mutex status_lock;
u8 portnum;
unsigned int is_superspeed:1;
+   unsigned int usb3_lpm_u1_permit:1;
+   unsigned int usb3_lpm_u2_permit:1;
 };
 
 #define to_usb_port(_dev) \
@@ -155,4 +159,3 @@ static inline int hub_port_debounce_be_stable(struct 
usb_hub *hub,
 {
return hub_port_debounce(hub, port1, false);
 }
-
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 2106183..cb18ce0 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -50,6 +50,72 @@ static ssize_t connect_type_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(connect_type);
 
+static ssize_t usb3_lpm_permit_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+   struct usb_port *port_dev = 

Re: [PATCH v2 1/3] usb: core: lpm: fix usb3_hardware_lpm sysfs node

[Lu Baolu]

On 11/13/2015 11:28 PM, Alan Stern wrote:

On Fri, 13 Nov 2015, Lu, Baolu wrote:


On 11/13/2015 12:20 AM, Alan Stern wrote:

On Thu, 12 Nov 2015, Lu Baolu wrote:


Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: sta...@vger.kernel.org
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>

...


--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,23 @@ static void usb_enable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
return;
}
   
-	if (usb_set_lpm_timeout(udev, state, timeout))

+   ret = usb_set_lpm_timeout(udev, state, timeout);
+   if (ret)
/* If we can't set the parent hub U1/U2 timeout,
 * device-initiated LPM won't be allowed either, so let the xHCI
 * host know that this link state won't be enabled.
 */
hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
-
/* Only a configured device will accept the Set Feature U1/U2_ENABLE */
else if (udev->actconfig)
usb_set_device_initiated_lpm(udev, state, true);
   
+	if (!ret) {

+   if (state == USB3_LPM_U1)
+   udev->usb3_lpm_u1_enabled = 1;
+   else if (state == USB3_LPM_U2)
+   udev->usb3_lpm_u2_enabled = 1;
+   }

This doesn't look right at all.  What happens if ret is 0 but the
device isn't configured?  You'll set the usb3_lpm_u*_enabled flag even
though LPM isn't really enabled.

Don't you want to set these flags inside the
usb_set_device_initiated_lpm() function, where you know whether the
action succeeded?  And leave this routine unchanged?

My understand is that both hub and device can initiate LPM.
As soon as usb_set_lpm_timeout(valid_timeout_value)
returns 0, the hub-initiated LPM is enabled. Thus, LPM is
enabled no matter the result of usb_set_device_initiated_lpm().
The only difference is whether device is able to initiate LPM.

On disable side, as soon as usb_set_lpm_timeout(0) return 0,
hub initiated LPM is disabled. Hub will disallows link to enter
U1/U2 as well, even device is initiating LPM. Hence LPM
is disabled as soon as hub LPM timeout set to 0, no matter
device-initiated LPM is disabled or not.

Then maybe you can add a comment explaining this.


Yes, I will add comments for this.



The patch still looks strange, though.  Your new code does this:

ret = usb_set_lpm_timeout(...);
if (ret)
...
else if (udev->actconfig)
...
if (!ret) {
if (state == USB3_LPM_U1)
...
}

It would be better to do this:

if (usb_set_lpm_timeout(...)) {
...
} else {
if (udev->actconfig)
...
if (state == USB3_LPM_U1)
...
}


Yes, this looks better. I will refactor this part of code.



Alan Stern



Thank you.
-Baolu


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[PATCH v3 3/3] usb: core: lpm: remove usb3_lpm_enabled in usb_device

[Lu Baolu]

Commit 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.")
adds usb3_lpm_enabled member to struct usb_device. There is no reference
to this member now. Hence, it could be removed.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 include/linux/usb.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/linux/usb.h b/include/linux/usb.h
index b79925d..89533ba 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -510,7 +510,6 @@ struct usb3_lpm_parameters {
  * @usb2_hw_lpm_besl_capable: device can perform USB2 hardware BESL LPM
  * @usb2_hw_lpm_enabled: USB2 hardware LPM is enabled
  * @usb2_hw_lpm_allowed: Userspace allows USB 2.0 LPM to be enabled
- * @usb3_lpm_enabled: USB3 hardware LPM enabled
  * @usb3_lpm_u1_enabled: USB3 hardware U1 LPM enabled
  * @usb3_lpm_u2_enabled: USB3 hardware U2 LPM enabled
  * @string_langid: language ID for strings
@@ -585,7 +584,6 @@ struct usb_device {
unsigned usb2_hw_lpm_besl_capable:1;
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
-   unsigned usb3_lpm_enabled:1;
unsigned usb3_lpm_u1_enabled:1;
unsigned usb3_lpm_u2_enabled:1;
int string_langid;
-- 
2.1.4

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[PATCH v3 1/3] usb: core: lpm: fix usb3_hardware_lpm sysfs node

[Lu Baolu]

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: sta...@vger.kernel.org
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 16 --
 Documentation/usb/power-management.txt  | 11 +-
 drivers/usb/core/hub.c  | 39 +
 drivers/usb/core/sysfs.c| 31 +-
 include/linux/usb.h |  4 
 5 files changed, 75 insertions(+), 26 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 3a4abfc..136ba17 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -134,19 +134,21 @@ Description:
enabled for the device. Developer can write y/Y/1 or n/N/0 to
the file to enable/disable the feature.
 
-What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm
-Date:  June 2015
+What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
+   /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
+Date:  November 2015
 Contact:   Kevin Strasser <kevin.stras...@linux.intel.com>
+   Lu Baolu <baolu...@linux.intel.com>
 Description:
If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
in to a xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS descriptor; if
-   the check is is passed and the host supports USB3 hardware LPM,
+   the check is passed and the host supports USB3 hardware LPM,
USB3 hardware LPM will be enabled for the device and the USB
-   device directory will contain a file named
-   power/usb3_hardware_lpm. The file holds a string value (enable
-   or disable) indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   device directory will contain two files named
+   power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
+   files hold a string value (enable or disable) indicating whether
+   or not USB3 hardware LPM U1 or U2 is enabled for the device.
 
 What:  /sys/bus/usb/devices/.../removable
 Date:  February 2012
diff --git a/Documentation/usb/power-management.txt 
b/Documentation/usb/power-management.txt
index 4a15c90..0a94ffe 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -537,17 +537,18 @@ relevant attribute files are usb2_hardware_lpm and 
usb3_hardware_lpm.
can write y/Y/1 or n/N/0 to the file to enable/disable
USB2 hardware LPM manually. This is for test purpose mainly.
 
-   power/usb3_hardware_lpm
+   power/usb3_hardware_lpm_u1
+   power/usb3_hardware_lpm_u2
 
When a USB 3.0 lpm-capable device is plugged in to a
xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS
descriptor; if the check is is passed and the host
supports USB3 hardware LPM, USB3 hardware LPM will be
-   enabled for the device and this file will be created.
-   The file holds a string value (enable or disable)
-   indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   enabled for the device and these files will be created.
+   The files hold a string value (enable or disable)
+   indicating whether or not USB3 hardware LPM U1 or U2
+   is enabled for the device.
 
USB Port Power Control
--
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bdeadc1..59f998e 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,30 @@ static void usb_enable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
return;
}
 
-   if (usb_set_lpm_timeout(udev, state, timeout))
+   if (usb_set_lpm_timeout(udev, state, timeout)) {
/* If we can't set the parent hub U1/U2 timeout,
 * device-initiated LPM won't be allowed either, so let the xHCI
 * host know that this link state won't be enabled.
 

Re: [PATCH v3 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk

[Lu Baolu]

Hi,

On 11/13/2015 11:34 PM, Dmitry Malkin wrote:

On Mon, 9 Nov 2015 15:38:33 +0800, Lu Baolu wrote:

On Intel platform, if the debug target is connected with debug
host, enabling DCE bit in command register leads to a hung bus
state. In the hung state, the host system will not see a port
connected status bit set. Hence debug target fails to be probed.

The state could be resolved by performing a port reset to the
debug port from the host xHCI. This patch introduces this work
around.

Is it correct to call this a "hung bus state"?  Wouldn't calling it
"hung port state" more appropriate?


Yes, "hung port state" is more appropriate.



I have observed this DCE-enable-related hung port state,
but the reason seemed to be different in my case:

Citing a note (sic!) from The Holy XHCI Spec, section 7.6.4.1:

If a Debug Host attempts to attach to a Debug Target before the DCE flag is set,
both ends of the link shall transition to the Inactive state.
So a Debug Host should periodically issue a Warm Reset
to ports that are Inactive to enable a connection to the DbC of the Debug 
Target.


Exactly. A formal workaround is to periodically issue Warm Resets to ports
from debug host.


Indeed, the inactive state is what I have observed (PLS field of port register 
PORTSC)
when the DCE bit is set to 1 with the cable already plugged in.

Now, according to my interpretation of The Hole USB 3.1 spec, section 7.5.2,
which says:

eSS.Inactive is a state where a link has failed Enhanced SuperSpeed operation.
A downstream port can only exit from this state when directed, or upon 
detection of
an absence of a far-end receiver termination (R RX-DC ) specified in Table 6-21,
or upon a Warm Reset.

It follows, that since hosts without DBC cannot listen to upstream requests,
the debug target-originated port reset requests (both hot and warm) will be 
ignored
by the debug host.


As above, a formal workaround is to issue Warm Reset periodically from debug
host, but that could cause much complexity. My quirk is to issue port 
reset just

*before* setting DCE bit. This quirk seems to work on several platforms.
(My debug host doesn't have DBC.)



This is the essence of the "hung port state" that I was able to observe.

Note, that this roadblock doesn't appear if you attach the cable /after/ 
enabling the DCE bit,


Yes.


or, alternatively, if the host has DBC.


Really? I haven't tried it yet.



And indeed, your quirk will work in the latter case, since the debug host hub
will be able to see the upstream reset request.


This quirk works as well if debug host doesn't have DBC. I didn't try a 
DBC-capable

debug host yet.



--
with best regards,
Dmitry Malkin


Thank you.
-Baolu


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Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

On 11/11/2015 10:25 AM, Dave Young wrote:

Hi,

On 11/11/15 at 09:32am, Lu, Baolu wrote:


On 11/10/2015 05:39 PM, Dave Young wrote:

Hi,

On 11/09/15 at 03:38pm, Lu Baolu wrote:

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.


I did a test with your previous patchset with the manually wired cable.
debug host detected the remote device, but later the devie automaticlly
disconnected and earlyprintk hangs.

Hi Dave,

What I have done is:

Retested it, seems it is not stable. I got a sucessful boot with earlyprintk
But only once and there was no "Press Y to continue", I just blindly pressed Y.

The other tests failed.


Problem seems to exist at the place where host and target sync with
each other.



Since it is not convinience to test, do you have way to enable the dbc
after kernel boot? like echo 1 to a sysfs file to enable it.


This is the first phase of code. I could do this in the next phase.
The problems exist in the interferer between DbC and the host
controller. They share the same power well so host reset, or
suspend/resume will cause DbC not work.


(1) Build a new kernel for debug target with this patch series applied.
(2) Add "earlyprintk=xdbc" to the kernel option of debug target. The
  "keep" option for early printk doesn't support yet. (That's my next
  target.)

(3) Boot the debug host, and disable USB runtime suspend:

# echo on > /sys/bus/pci/devices//power/control
# echo on | tee /sys/bus/usb/devices/*/power/control

(4) Boot the debug target. Check the dmesg message on debug host.

# tail -f /var/log/kern.log

Nov 12 01:27:50 allen-ult kernel: [ 1815.983374] usb 4-3: new SuperSpeed USB
device number 4 using xhci_hcd
Nov 12 01:27:50 allen-ult kernel: [ 1815.999595] usb 4-3: LPM exit latency
is zeroed, disabling LPM.
Nov 12 01:27:50 allen-ult kernel: [ 1815.999899] usb 4-3: New USB device
found, idVendor=1d6b, idProduct=0004
Nov 12 01:27:50 allen-ult kernel: [ 1815.02] usb 4-3: New USB device
strings: Mfr=1, Product=2, SerialNumber=3
Nov 12 01:27:50 allen-ult kernel: [ 1815.03] usb 4-3: Product: Remote
GDB
Nov 12 01:27:50 allen-ult kernel: [ 1815.04] usb 4-3: Manufacturer:
Linux
Nov 12 01:27:50 allen-ult kernel: [ 1815.05] usb 4-3: SerialNumber: 0001
Nov 12 01:27:50 allen-ult kernel: [ 1816.000240] usb_debug 4-3:1.0: xhci_dbc
converter detected
Nov 12 01:27:50 allen-ult kernel: [ 1816.000360] usb 4-3: xhci_dbc converter
now attached to ttyUSB0

(5) Host has completed enumeration of debug device. Start "minicom" on debug
host.


Most times I have no chance to run minicom before the usb disconnection here.


I will send you a new version for test later. By the way, which hardware
are you using for test?




Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Jan  1 2014, 17:13:19.
Port /dev/ttyUSB0, 01:28:02

Press CTRL-A Z for help on special keys

Press Y to continue...

(6) You should be able to see "Press Y to continue..." (if not, try pressing
Enter key)
Press Y key, debug target should go ahead with boot and early boot messages
should show in mincom.

Press Y to continue...
[0.00] Initializing cgroup subsys cpuset
[0.00] Initializing cgroup subsys cpu
[0.00] Initializing cgroup subsys cpuacct
[0.00] Linux version 4.3.0-rc7+ (allen@blu-skl) (gcc version 4.8.4
(Ubuntu 4.8.4-2ubuntu1~14.04) 5
[0.00] Command line: BOOT_IMAGE=/boot/vmlinuz-4.3.0-rc7+
root=UUID=5a2fb856-0238-4b6e-aa45-beeccb7
[0.00] KERNEL supported cpus:

[...skipped...]

[0.00]  Offload RCU callbacks from CPUs: 0-7.
[0.00] Console: colour dummy device 80x25
[0.00] console [tty0] enabled
[0.00] bootconsole [earlyxdbc0] disabled


So "the devie automaticlly disconnected and earlyprintk hangs" happens in
which step?


Here is some log on host side.

[ 1568.052135] usb 2-2: new SuperSpeed USB device number 5 using xhci_hcd
[ 1568.063416] usb 2-2: LPM exit latency is zeroed, disabling LPM.
[ 1568.063750] usb 2-2: New USB device found, idVendor=1d6b, idProduct=0004
[ 1568.063751] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1568.063752] usb 2-2: Product: Remote GDB
[ 1568.063753] usb 2-2: Manufacturer: Linux
[ 1568.063754] usb 2-2: SerialNumber: 0001
[ 1568.065580] usb_debug 2-2:1.0: xhci_dbc converter detected
[ 1568.066309] usb 2-2: xhci_dbc converter now attached to ttyUSB0
[ 1580.464706] usb 2-2: USB disconnect, device number 5
[ 1580.464996] xhci_dbc ttyUSB0: xhci_dbc converter now disconnected from 
ttyUSB0
[ 1580.465062] usb_debug 2-2:1.0: device disconnected
[ 1580.670743] usb 2-2: new SuperSpeed USB device number 6 using xhci_hcd
[ 1580.682068] usb 2-2: LPM exit latency is zeroed, disabling LPM.
[ 1580.682667] usb 2-2: New USB device found, idVendor=1d6b, idProduct=0004
[ 1580.682672] usb 2-2: New USB device strings: M

Re: [PATCH v3 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu, Baolu]

On 11/10/2015 05:36 PM, Dave Young wrote:

[snip]


diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 000..0192ac4
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,100 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+
+#include "xhci.h"
+
+/*
+ * Return the register offset of a extended capability specified
+ * by @cap_id. Return 0 if @cap_id capability is not supported or
+ * in error cases.
+ */
+static int get_extended_capability_offset(struct xhci_hcd *xhci,
+   int cap_id)
+{
+   u32 cap_reg;
+   unsigned long   flags;
+   int offset;
+   void __iomem*base = (void __iomem *) xhci->cap_regs;
+   struct usb_hcd  *hcd = xhci_to_hcd(xhci);
+   int time_to_leave = XHCI_EXT_MAX_CAPID;
+
+   spin_lock_irqsave(>lock, flags);
+
+   offset = xhci_find_next_cap_offset(base, XHCI_HCC_PARAMS_OFFSET);
+   if (!HCD_HW_ACCESSIBLE(hcd) || !offset) {
+   spin_unlock_irqrestore(>lock, flags);
+   return 0;
+   }
+
+   while (time_to_leave--) {
+   cap_reg = readl(base + offset);
+
+   if (XHCI_EXT_CAPS_ID(cap_reg) == cap_id)
+   break;
+
+   offset = xhci_find_next_cap_offset(base, offset);
+   if (!offset)
+   break;
+   }
+
+   spin_unlock_irqrestore(>lock, flags);

I'm not sure spin_lock is good and necessary here, also seems there's already


The lock is unnecessary here. I will remove it.


a function to find the cap offset:
xhci_find_ext_cap_by_id() in xhci-ext-caps.h


Yes, I will refactor the code.

Thanks,
Baolu



+
+   return offset;
+}
+

Thanks
Dave



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Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

On 11/10/2015 05:39 PM, Dave Young wrote:

Hi,

On 11/09/15 at 03:38pm, Lu Baolu wrote:

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.


I did a test with your previous patchset with the manually wired cable.
debug host detected the remote device, but later the devie automaticlly
disconnected and earlyprintk hangs.


Hi Dave,

What I have done is:

(1) Build a new kernel for debug target with this patch series applied.
(2) Add "earlyprintk=xdbc" to the kernel option of debug target. The
 "keep" option for early printk doesn't support yet. (That's my next
 target.)

(3) Boot the debug host, and disable USB runtime suspend:

# echo on > /sys/bus/pci/devices//power/control
# echo on | tee /sys/bus/usb/devices/*/power/control

(4) Boot the debug target. Check the dmesg message on debug host.

# tail -f /var/log/kern.log

Nov 12 01:27:50 allen-ult kernel: [ 1815.983374] usb 4-3: new SuperSpeed 
USB device number 4 using xhci_hcd
Nov 12 01:27:50 allen-ult kernel: [ 1815.999595] usb 4-3: LPM exit 
latency is zeroed, disabling LPM.
Nov 12 01:27:50 allen-ult kernel: [ 1815.999899] usb 4-3: New USB device 
found, idVendor=1d6b, idProduct=0004
Nov 12 01:27:50 allen-ult kernel: [ 1815.02] usb 4-3: New USB device 
strings: Mfr=1, Product=2, SerialNumber=3
Nov 12 01:27:50 allen-ult kernel: [ 1815.03] usb 4-3: Product: 
Remote GDB
Nov 12 01:27:50 allen-ult kernel: [ 1815.04] usb 4-3: Manufacturer: 
Linux

Nov 12 01:27:50 allen-ult kernel: [ 1815.05] usb 4-3: SerialNumber: 0001
Nov 12 01:27:50 allen-ult kernel: [ 1816.000240] usb_debug 4-3:1.0: 
xhci_dbc converter detected
Nov 12 01:27:50 allen-ult kernel: [ 1816.000360] usb 4-3: xhci_dbc 
converter now attached to ttyUSB0


(5) Host has completed enumeration of debug device. Start "minicom" on 
debug host.



Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Jan  1 2014, 17:13:19.
Port /dev/ttyUSB0, 01:28:02

Press CTRL-A Z for help on special keys

Press Y to continue...

(6) You should be able to see "Press Y to continue..." (if not, try 
pressing Enter key)
Press Y key, debug target should go ahead with boot and early boot 
messages should show in mincom.


Press Y to continue...
[0.00] Initializing cgroup subsys cpuset
[0.00] Initializing cgroup subsys cpu
[0.00] Initializing cgroup subsys cpuacct
[0.00] Linux version 4.3.0-rc7+ (allen@blu-skl) (gcc version 
4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04) 5
[0.00] Command line: BOOT_IMAGE=/boot/vmlinuz-4.3.0-rc7+ 
root=UUID=5a2fb856-0238-4b6e-aa45-beeccb7

[0.00] KERNEL supported cpus:

[...skipped...]

[0.00]  Offload RCU callbacks from CPUs: 0-7.
[0.00] Console: colour dummy device 80x25
[0.00] console [tty0] enabled
[0.00] bootconsole [earlyxdbc0] disabled


So "the devie automaticlly disconnected and earlyprintk hangs" happens 
in which step?


Thanks,
Baolu



I have not got more time, will try your new patchset when I have time.

Thanks
Dave



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Re: [PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

On 11/11/2015 10:25 AM, Dave Young wrote:

[ 1616.823351] usb 2-2: new SuperSpeed USB device number 8 using xhci_hcd
[ 1616.834520] usb 2-2: LPM exit latency is zeroed, disabling LPM.
[ 1616.834856] usb 2-2: New USB device found, idVendor=1d6b, idProduct=0004
[ 1616.834858] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1616.834859] usb 2-2: Product: Remote GDB
[ 1616.834860] usb 2-2: Manufacturer: Linux
[ 1616.834860] usb 2-2: SerialNumber: 0001
[ 1616.836715] usb_debug 2-2:1.0: xhci_dbc converter detected
[ 1616.837327] usb 2-2: xhci_dbc converter now attached to ttyUSB0
[ 1622.719311] usb 2-2: USB disconnect, device number 8

 Hi Dave,

I revisited the kernel log. It seems the debug host enumerated
the debug target successfully. Can you please check the
minicom configuration?

The configure on my debug host looks like below.

Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Jan  1 2014, 17:13:19.
Port /dev/ttyUSB0, 01:28:02

Rate: 115200

Please make sure you have disabled runtime power management
for USB devices and host controller in debug host. And sometimes,
reboot the debug host helps when enumeration fails.

Thanks,
Baolu
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[PATCH 0/3] usb: core: lpm: add sysfs node for usb3 lpm permit

[Lu Baolu]

Hi,

This patch series is about to add a sysfs attribute, through which
users can disable or enable USB3 LPM (link power management) from
a USB port. Once LPM is disabled from the USB port, LPM between the
downstreaming device and the hub port will not be activated. This
helps users to use any LPM-unfriendly USB devices on any released
Linux kernels.

This patch series contains a fix and a cleanup as well.

Thanks,
Baolu

Lu Baolu (3):
  usb: core: lpm: fix usb3_hardware_lpm sysfs node
  usb: core: lpm: add sysfs node for usb3 lpm permit
  usb: core: lpm: remove usb3_lpm_enabled in usb_device

 Documentation/ABI/testing/sysfs-bus-usb | 27 +++---
 Documentation/usb/power-management.txt  | 11 ++--
 drivers/usb/core/hub.c  | 33 +---
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 drivers/usb/core/sysfs.c| 31 ++--
 include/linux/usb.h |  3 +-
 7 files changed, 172 insertions(+), 27 deletions(-)

-- 
2.1.4

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[PATCH 1/3] usb: core: lpm: fix usb3_hardware_lpm sysfs node

[Lu Baolu]

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

This patch should be back-ported to kernels as old as 4.3,
that contains Commit 655fe4effe0f ("usbcore: add sysfs support
to xHCI usb3 hardware LPM").

Cc: sta...@vger.kernel.org
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 16 +---
 Documentation/usb/power-management.txt  | 11 ++-
 drivers/usb/core/hub.c  | 20 ++--
 drivers/usb/core/sysfs.c| 31 ++-
 include/linux/usb.h |  2 ++
 5 files changed, 57 insertions(+), 23 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 3a4abfc..136ba17 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -134,19 +134,21 @@ Description:
enabled for the device. Developer can write y/Y/1 or n/N/0 to
the file to enable/disable the feature.
 
-What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm
-Date:  June 2015
+What:  /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
+   /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
+Date:  November 2015
 Contact:   Kevin Strasser <kevin.stras...@linux.intel.com>
+   Lu Baolu <baolu...@linux.intel.com>
 Description:
If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
in to a xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS descriptor; if
-   the check is is passed and the host supports USB3 hardware LPM,
+   the check is passed and the host supports USB3 hardware LPM,
USB3 hardware LPM will be enabled for the device and the USB
-   device directory will contain a file named
-   power/usb3_hardware_lpm. The file holds a string value (enable
-   or disable) indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   device directory will contain two files named
+   power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
+   files hold a string value (enable or disable) indicating whether
+   or not USB3 hardware LPM U1 or U2 is enabled for the device.
 
 What:  /sys/bus/usb/devices/.../removable
 Date:  February 2012
diff --git a/Documentation/usb/power-management.txt 
b/Documentation/usb/power-management.txt
index 4a15c90..0a94ffe 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -537,17 +537,18 @@ relevant attribute files are usb2_hardware_lpm and 
usb3_hardware_lpm.
can write y/Y/1 or n/N/0 to the file to enable/disable
USB2 hardware LPM manually. This is for test purpose mainly.
 
-   power/usb3_hardware_lpm
+   power/usb3_hardware_lpm_u1
+   power/usb3_hardware_lpm_u2
 
When a USB 3.0 lpm-capable device is plugged in to a
xHCI host which supports link PM, it will check if U1
and U2 exit latencies have been set in the BOS
descriptor; if the check is is passed and the host
supports USB3 hardware LPM, USB3 hardware LPM will be
-   enabled for the device and this file will be created.
-   The file holds a string value (enable or disable)
-   indicating whether or not USB3 hardware LPM is
-   enabled for the device.
+   enabled for the device and these files will be created.
+   The files hold a string value (enable or disable)
+   indicating whether or not USB3 hardware LPM U1 or U2
+   is enabled for the device.
 
USB Port Power Control
--
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bdeadc1..4eb7369 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3875,17 +3875,23 @@ static void usb_enable_link_state(struct usb_hcd *hcd, 
struct usb_device *udev,
return;
}
 
-   if (usb_set_lpm_timeout(udev, state, timeout))
+   ret = usb_set_lpm_timeout(udev, state, timeout);
+   if (ret)
/* If we can't set the parent hub U1/U2 timeout,
 * device-initiated LPM won't be allowed either, so let the xHCI
 * host know that this link state won't be enabled.
 

[PATCH 2/3] usb: core: lpm: add sysfs node for usb3 lpm permit

[Lu Baolu]

USB3 LPM is default on in Linux kernel if both xHCI host controller
and the USB devices declare to be LPM-capable. Unfortunately, some
devices are known to work well with LPM disabled, but to be broken
if LPM is enabled, although it declares the LPM capability.  Users
won't be able to use this kind of devices, until someone puts them
in the kernel blacklist and gets the kernel upgraded.

This patch adds a sysfs node to permit or forbit USB3 LPM U1 or U2
entry for a port. The settings apply to both before and after device
enumeration. Supported values are "0" - neither u1 nor u2 permitted,
"u1" - only u1 is permitted, "u2" - only u2 is permitted, "u1_u2" -
both u1 and u2 are permitted. With this interface, users can use an
LPM-unfriendly USB device on a released Linux kernel.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Zhuang Jin Can <jin.can.zhu...@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 11 
 drivers/usb/core/hub.c  | 15 +-
 drivers/usb/core/hub.h  |  5 +-
 drivers/usb/core/port.c | 89 -
 4 files changed, 116 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb 
b/Documentation/ABI/testing/sysfs-bus-usb
index 136ba17..0bd731c 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -189,6 +189,17 @@ Description:
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
 
+What:  /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
+Date:  November 2015
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   Some USB3.0 devices are not friendly to USB3 LPM.  
usb3_lpm_permit
+   attribute allows enabling/disabling usb3 lpm of a port. It takes
+   effect both before and after a usb device is enumerated. 
Supported
+   values are "0" if both u1 and u2 are NOT permitted, "u1" if 
only u1
+   is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 
and
+   u2 are permitted.
+
 What:  /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:  May 2013
 Contact:   Mathias Nyman <mathias.ny...@linux.intel.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 4eb7369..9df568e 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4007,6 +4007,8 @@ EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);
 void usb_enable_lpm(struct usb_device *udev)
 {
struct usb_hcd *hcd;
+   struct usb_hub *hub;
+   struct usb_port *port_dev;
 
if (!udev || !udev->parent ||
udev->speed != USB_SPEED_SUPER ||
@@ -4026,8 +4028,17 @@ void usb_enable_lpm(struct usb_device *udev)
if (udev->lpm_disable_count > 0)
return;
 
-   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
-   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
+   hub = usb_hub_to_struct_hub(udev->parent);
+   if (!hub)
+   return;
+
+   port_dev = hub->ports[udev->portnum - 1];
+
+   if (port_dev->usb3_lpm_u1_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U1);
+
+   if (port_dev->usb3_lpm_u2_permit)
+   usb_enable_link_state(hcd, udev, USB3_LPM_U2);
 }
 EXPORT_SYMBOL_GPL(usb_enable_lpm);
 
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 688817f..45d070d 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -92,6 +92,8 @@ struct usb_hub {
  * @status_lock: synchronize port_event() vs usb_port_{suspend|resume}
  * @portnum: port index num based one
  * @is_superspeed cache super-speed status
+ * @usb3_lpm_u1_permit: whether USB3 U1 LPM is permitted.
+ * @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted.
  */
 struct usb_port {
struct usb_device *child;
@@ -104,6 +106,8 @@ struct usb_port {
struct mutex status_lock;
u8 portnum;
unsigned int is_superspeed:1;
+   unsigned int usb3_lpm_u1_permit:1;
+   unsigned int usb3_lpm_u2_permit:1;
 };
 
 #define to_usb_port(_dev) \
@@ -155,4 +159,3 @@ static inline int hub_port_debounce_be_stable(struct 
usb_hub *hub,
 {
return hub_port_debounce(hub, port1, false);
 }
-
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 2106183..cb18ce0 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -50,6 +50,72 @@ static ssize_t connect_type_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(connect_type);
 
+static ssize_t usb3_lpm_permit_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+   struct usb_port *port_dev = 

[PATCH 3/3] usb: core: lpm: remove usb3_lpm_enabled in usb_device

[Lu Baolu]

Commit 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.")
adds usb3_lpm_enabled member to struct usb_device. There is no reference
to this member now. Hence, it could be removed.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 include/linux/usb.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 211664f..036e4a5 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -583,7 +583,6 @@ struct usb_device {
unsigned usb2_hw_lpm_besl_capable:1;
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
-   unsigned usb3_lpm_enabled:1;
unsigned usb3_lpm_u1_enabled:1;
unsigned usb3_lpm_u2_enabled:1;
int string_langid;
-- 
2.1.4

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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

On 11/09/2015 05:27 PM, Steinar H. Gunderson wrote:

On Mon, Nov 09, 2015 at 01:02:50PM +0800, Lu, Baolu wrote:

We've got below facts:

1. One card works well w/ or w/o LPM enabled.

No, this isn't right. One card works well without LPM; it does work with LPM
but not well. There are ping timeouts that cause disconnects, especially
during the first packets.


I wasn't aware of this kind of issue.




2. Two cards work well w/o LPM, but not work w/ LPM. The error
 is "not enough bus bandwidth".

Correct.


We can come to a conclusion that "LPM consumes extra usb bus
bandwidth, this extra bandwidth could cause device not to work
due to limited bandwidth resources."

I have a patch attached in this email. It can disable LPM for any
devices during run time. Do you mind having a try? You can follow
below steps:

You saw Alan's blacklisting patch, right? It works perfectly for me.
But I'll be happy to try yours as well.


Yes, I know that you already have a patch and it works for you.
I am in favor of Alan's patch. You can go ahead with that patch.

I just want to find a way that users can use an LPM-unfriendly
device, but don't need to customize a kernel or wait until the
the quirk patch gets merged.



/* Steinar */


Thanks,
Baolu
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[PATCH v3 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk

[Lu Baolu]

On Intel platform, if the debug target is connected with debug
host, enabling DCE bit in command register leads to a hung bus
state. In the hung state, the host system will not see a port
connected status bit set. Hence debug target fails to be probed.

The state could be resolved by performing a port reset to the
debug port from the host xHCI. This patch introduces this work
around.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 52 
 include/linux/usb/xhci-dbc.h |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 22a1de9..6b23f09 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -255,6 +255,8 @@ static void __iomem *xdbc_map_pci_mmio(u32 bus,
xdbcp->bar = bar;
xdbcp->xhci_base = base;
xdbcp->xhci_length = sz64;
+   xdbcp->vendor = read_pci_config_16(bus, dev, func, PCI_VENDOR_ID);
+   xdbcp->device = read_pci_config_16(bus, dev, func, PCI_DEVICE_ID);
 
if (length)
*length = sz64;
@@ -651,6 +653,52 @@ static int xdbc_mem_init(void)
return 0;
 }
 
+static void xdbc_reset_debug_port_callback(int cap_offset, void *data)
+{
+   u8 major;
+   u32 val, port_offset, port_count;
+   u32 cap_length;
+   void __iomem *ops_reg;
+   void __iomem *portsc;
+   int i;
+
+   val = readl(xdbcp->xhci_base + cap_offset);
+   major = (u8) XHCI_EXT_PORT_MAJOR(val);
+
+   /* only reset super-speed port */
+   if (major != 0x3)
+   return;
+
+   val = readl(xdbcp->xhci_base + cap_offset + 8);
+   port_offset = XHCI_EXT_PORT_OFF(val);
+   port_count = XHCI_EXT_PORT_COUNT(val);
+   xdbc_trace("Extcap Port offset %d count %d\n",
+   port_offset, port_count);
+
+   cap_length = readl(xdbcp->xhci_base) & 0xff;
+   ops_reg = xdbcp->xhci_base + cap_length;
+
+   port_offset--;
+   for (i = port_offset; i < (port_offset + port_count); i++) {
+   portsc = ops_reg + 0x400 + i * 0x10;
+   val = readl(portsc);
+   /* reset the port if CCS bit is cleared */
+   if (!(val & 0x1))
+   writel(val | (1 << 4), portsc);
+   }
+}
+
+static void xdbc_reset_debug_port(void)
+{
+   xdbc_walk_excap(xdbcp->bus,
+   xdbcp->dev,
+   xdbcp->func,
+   XHCI_EXT_CAPS_PROTOCOL,
+   false,
+   xdbc_reset_debug_port_callback,
+   NULL);
+}
+
 /*
  * xdbc_start: start DbC
  *
@@ -669,6 +717,10 @@ static int xdbc_start(void)
return -ENODEV;
}
 
+   /* reset port to avoid bus hang */
+   if (xdbcp->vendor == PCI_VENDOR_ID_INTEL)
+   xdbc_reset_debug_port();
+
/* wait for port connection */
if (handshake(>xdbc_reg->portsc, PORTSC_CCS,
PORTSC_CCS, 500, 100) < 0) {
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 153fb87..fc0ef9a 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -128,6 +128,8 @@ struct xdbc_state {
u32 dev;
u32 func;
u8  bar;
+   u16 vendor;
+   u16 device;
void __iomem*xhci_base;
size_t  xhci_length;
 #defineXDBC_PCI_MAX_BUSES  256
-- 
2.1.4

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[PATCH v3 05/12] usb: xhci: dbc: add debug buffer

[Lu Baolu]

"printk" is not suitable for dbc debugging especially when console
is in usage. This patch adds a debug buffer in dbc driver and puts
the debug messages in this local buffer. The debug buffer could be
dumped whenever the console is not in use. This part of code will
not be visible unless DBC_DEBUG is defined.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 62 ++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 6b23f09..b36a527 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,8 +32,64 @@ static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
 #ifdef DBC_DEBUG
-/* place holder */
-#definexdbc_trace  printk
+#defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
+#defineMSG_MAX_LINE128
+static char xdbc_debug_buf[XDBC_DEBUG_BUF_SIZE];
+static void xdbc_trace(const char *fmt, ...)
+{
+   int i, size;
+   va_list args;
+   static int pos;
+   char temp_buf[MSG_MAX_LINE];
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   return;
+
+   memset(temp_buf, 0, MSG_MAX_LINE);
+   va_start(args, fmt);
+   vsnprintf(temp_buf, MSG_MAX_LINE - 1, fmt, args);
+   va_end(args);
+
+   i = 0;
+   size = strlen(temp_buf);
+   while (i < size) {
+   xdbc_debug_buf[pos] = temp_buf[i];
+   pos++;
+   i++;
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   break;
+   }
+}
+
+static void xdbc_dump_debug_buffer(void)
+{
+   int index = 0;
+   int count = 0;
+   char dump_buf[MSG_MAX_LINE];
+
+   xdbc_trace("The end of DbC trace buffer\n");
+   pr_notice("DBC debug buffer:\n");
+   memset(dump_buf, 0, MSG_MAX_LINE);
+
+   while (index < XDBC_DEBUG_BUF_SIZE) {
+   if (!xdbc_debug_buf[index])
+   break;
+
+   if (xdbc_debug_buf[index] == '\n' ||
+   count >= MSG_MAX_LINE - 1) {
+   pr_notice("DBC: @%08x %s\n", index, dump_buf);
+   memset(dump_buf, 0, MSG_MAX_LINE);
+   count = 0;
+   } else {
+   dump_buf[count] = xdbc_debug_buf[index];
+   count++;
+   }
+
+   index++;
+   }
+}
+
 static void xdbc_dbg_dump_regs(char *str)
 {
if (!xdbcp->xdbc_reg) {
@@ -165,6 +221,7 @@ static void xdbc_dbg_dump_data(char *str)
 
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
+static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
 #endif /* DBC_DEBUG */
@@ -832,6 +889,7 @@ int __init early_xdbc_init(char *s)
pr_notice("failed to setup xHCI DbC connection\n");
xdbcp->xhci_base = NULL;
xdbcp->xdbc_reg = NULL;
+   xdbc_dump_debug_buffer();
return ret;
}
 
-- 
2.1.4

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[PATCH v3 07/12] usb: xhci: dbc: handle dbc-configured exit

[Lu Baolu]

DbC might exit configured state in some cases (refer to 7.6.4.4 in
xHCI spec 1.1). Software needs detect and clear this situation by
clearing DCCTRL.DCR and wait until the DbC configured before read
or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 28 
 1 file changed, 28 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index f51daa4..8a5a51f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1153,6 +1153,29 @@ static int xdbc_wait_until_bulk_done(struct xdbc_trb 
*trb, int loops)
return -EIO;
 }
 
+static int xdbc_wait_until_dbc_configured(void)
+{
+   int timeout = 0;
+   u32 reg;
+
+   /* Port exits configured state */
+   reg = readl(>xdbc_reg->control);
+   if (!(reg & CTRL_DRC))
+   return 0;
+
+   /* clear run change bit (RW1C) */
+   writel(reg | CTRL_DRC, >xdbc_reg->control);
+
+   do {
+   if (readl(>xdbc_reg->control) & CTRL_DCR)
+   return 0;
+
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1167,6 +1190,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EINVAL;
}
 
+   if (xdbc_wait_until_dbc_configured()) {
+   xdbc_trace("%s: hardware not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v3 03/12] usb: xhci: dbc: probe and setup xhci debug capability

[Lu Baolu]

xHCI debug capability (DbC) is an optional functionality provided
by an xHCI host controller. Software learns this capability by
walking through the extended capability list in mmio of the host.

This patch introduces the code to probe and initialize the debug
capability hardware during early boot. With hardware initialization
done, the debug target (system under debug which has DbC enabled)
will present a debug device through the debug port. The debug device
is fully compliant with the USB framework and provides the equivalent
of a very high performance (USB3) full-duplex serial link between the
debug host and target.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 MAINTAINERS  |   7 +
 arch/x86/Kconfig.debug   |  12 +
 drivers/usb/early/Makefile   |   1 +
 drivers/usb/early/xhci-dbc.c | 787 +++
 include/linux/usb/xhci-dbc.h | 187 ++
 5 files changed, 994 insertions(+)
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 0425167..585a369 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11040,6 +11040,13 @@ S: Supported
 F: drivers/usb/host/xhci*
 F: drivers/usb/host/pci-quirks*
 
+USB XHCI DEBUG PORT
+M:     Lu Baolu <baolu...@linux.intel.com>
+L: linux-usb@vger.kernel.org
+S: Supported
+F: drivers/usb/early/xhci-dbc.c
+F: include/linux/usb/xhci-dbc.h
+
 USB ZD1201 DRIVER
 L: linux-wirel...@vger.kernel.org
 W: http://linux-lc100020.sourceforge.net
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index d8c0d32..8d95abd 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -65,6 +65,18 @@ config EARLY_PRINTK_EFI
  This is useful for kernel debugging when your machine crashes very
  early before the console code is initialized.
 
+config EARLY_PRINTK_XDBC
+   bool "Early printk via xHCI debug port"
+   depends on EARLY_PRINTK && PCI
+   ---help---
+ Write kernel log output directly into the xHCI debug port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash.
+
 config X86_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
diff --git a/drivers/usb/early/Makefile b/drivers/usb/early/Makefile
index 24bbe51..2db5906 100644
--- a/drivers/usb/early/Makefile
+++ b/drivers/usb/early/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_EARLY_PRINTK_DBGP) += ehci-dbgp.o
+obj-$(CONFIG_EARLY_PRINTK_XDBC) += xhci-dbc.o
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
new file mode 100644
index 000..22a1de9
--- /dev/null
+++ b/drivers/usb/early/xhci-dbc.c
@@ -0,0 +1,787 @@
+/**
+ * xhci-dbc.c - xHCI debug capability driver
+ *
+ * Copyright (C) 2015 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ * Some code shared with EHCI debug port and xHCI driver.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include "../host/xhci.h"
+
+#defineXDBC_PROTOCOL   1   /* GNU Remote Debug Command Set 
*/
+#defineXDBC_VENDOR_ID  0x1d6b  /* Linux Foundation 0x1d6b */
+#defineXDBC_PRODUCT_ID 0x0004  /* __le16 idProduct; device 
0004 */
+#defineXDBC_DEVICE_REV 0x0010  /* 0.10 */
+
+static struct xdbc_state xdbc_stat;
+static struct xdbc_state *xdbcp = _stat;
+
+#ifdef DBC_DEBUG
+/* place holder */
+#definexdbc_trace  printk
+static void xdbc_dbg_dump_regs(char *str)
+{
+   if (!xdbcp->xdbc_reg) {
+   xdbc_trace("register not mapped\n");
+   return;
+   }
+
+   xdbc_trace("XDBC registers: %s\n", str);
+   xdbc_trace("  Capability: %08x\n",
+   readl(>xdbc_reg->capability));
+   xdbc_trace("  Door bell: %08x\n",
+   readl(>xdbc_reg->doorbell));
+   xdbc_trace("  Event Ring Segment Table Size: %08x\n",
+   readl(>xdbc_reg->ersts));
+   xdbc_trace("  Event Ring Segment Table Base Address: %16llx\n",
+   xdbc_read64(>xdbc_reg->erstba));
+   xdbc_trace("  Event Ring Dequeue Pointer: %16llx\n",
+   xdbc_read64(>xdbc_reg->erdp));
+   xdbc

[PATCH v3 09/12] x86: early_printk: add USB3 debug port earlyprintk support

[Lu Baolu]

Add support for early printk by writing debug messages to the USB3
debug port. Users can use this type of early printk by specifying
kernel parameter of "earlyprintk=xdbc". This gives users a chance
of providing debug output.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/kernel-parameters.txt |  1 +
 arch/x86/kernel/early_printk.c  |  5 +
 drivers/usb/early/xhci-dbc.c| 43 +
 include/linux/usb/xhci-dbc.h|  5 +
 4 files changed, 54 insertions(+)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index 22a4b68..b65b07f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1032,6 +1032,7 @@ bytes respectively. Such letter suffixes can also be 
entirely omitted.
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
earlyprintk=pciserial,bus:device.function[,baudrate]
+   earlyprintk=xdbc[xhciController#]
 
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index eec40f5..5341a16 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -373,6 +374,10 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
early_console_register(_dbgp_console, keep);
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   if (!strncmp(buf, "xdbc", 4) && !early_xdbc_init(buf + 4))
+   early_console_register(_xdbc_console, keep);
+#endif
 #ifdef CONFIG_HVC_XEN
if (!strncmp(buf, "xen", 3))
early_console_register(_console, keep);
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index aaf655f..68a7139 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -10,6 +10,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include 
 #include 
 #include 
 #include 
@@ -1332,3 +1333,45 @@ int xdbc_bulk_write(const char *bytes, int size)
 
return ret;
 }
+
+/*
+ * Start a bulk-in or bulk-out transfer, wait until transfer completion
+ * or error. Return the count of actually transferred bytes or error.
+ */
+static void early_xdbc_write(struct console *con, const char *str, u32 n)
+{
+   int chunk, ret;
+   static char buf[XDBC_MAX_PACKET];
+   int use_cr = 0;
+
+   if (!xdbcp->xdbc_reg)
+   return;
+   memset(buf, 0, XDBC_MAX_PACKET);
+   while (n > 0) {
+   for (chunk = 0; chunk < XDBC_MAX_PACKET && n > 0;
+str++, chunk++, n--) {
+   if (!use_cr && *str == '\n') {
+   use_cr = 1;
+   buf[chunk] = '\r';
+   str--;
+   n++;
+   continue;
+   }
+   if (use_cr)
+   use_cr = 0;
+   buf[chunk] = *str;
+   }
+   if (chunk > 0) {
+   ret = xdbc_bulk_write(buf, chunk);
+   if (ret < 0)
+   break;
+   }
+   }
+}
+
+struct console early_xdbc_console = {
+   .name = "earlyxdbc",
+   .write =early_xdbc_write,
+   .flags =CON_PRINTBUFFER,
+   .index =-1,
+};
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 289ba58..a556eb8 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -216,4 +216,9 @@ struct xdbc_state {
 #definexdbc_read64(regs)   xhci_read_64(NULL, (regs))
 #definexdbc_write64(val, regs) xhci_write_64(NULL, (val), (regs))
 
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+extern int early_xdbc_init(char *s);
+extern struct console early_xdbc_console;
+#endif /* CONFIG_EARLY_PRINTK_XDBC */
+
 #endif /* __LINUX_XHCI_DBC_H */
-- 
2.1.4

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[PATCH v3 06/12] usb: xhci: dbc: add bulk out and bulk in interfaces

[Lu Baolu]

This patch adds interfaces for bulk out and bulk in ops. These
interfaces could be used to implement early printk bootconsole
or hook to various system debuggers.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 373 +++
 include/linux/usb/xhci-dbc.h |  30 
 2 files changed, 403 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index b36a527..f51daa4 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -219,11 +219,21 @@ static void xdbc_dbg_dump_data(char *str)
xdbc_dbg_dump_string("String Descriptor:");
 }
 
+static void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str)
+{
+   xdbc_trace("DBC trb: %s\n", str);
+   xdbc_trace("@%016llx %08x %08x %08x %08x\n", (u64)__pa(trb),
+   le32_to_cpu(trb->field[0]),
+   le32_to_cpu(trb->field[1]),
+   le32_to_cpu(trb->field[2]),
+   le32_to_cpu(trb->field[3]));
+}
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
 static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
+static inline void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str) { }
 #endif /* DBC_DEBUG */
 
 /*
@@ -334,6 +344,7 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
static char in_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char out_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char table_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+   static char bulk_buf_page[PAGE_SIZE] __aligned(PAGE_SIZE);
 
switch (type) {
case XDBC_PAGE_EVENT:
@@ -348,6 +359,9 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
case XDBC_PAGE_TABLE:
virt = (void *)table_page;
break;
+   case XDBC_PAGE_BUFFER:
+   virt = (void *)bulk_buf_page;
+   break;
default:
return NULL;
}
@@ -707,6 +721,12 @@ static int xdbc_mem_init(void)
dev_info = cpu_to_le32((XDBC_DEVICE_REV << 16) | XDBC_PRODUCT_ID);
writel(dev_info, >xdbc_reg->devinfo2);
 
+   /* get and store the transfer buffer */
+   xdbcp->out_buf = xdbc_get_page(>out_dma,
+   XDBC_PAGE_BUFFER);
+   xdbcp->in_buf = xdbcp->out_buf + XDBC_MAX_PACKET;
+   xdbcp->in_dma = xdbcp->out_dma + XDBC_MAX_PACKET;
+
return 0;
 }
 
@@ -802,6 +822,9 @@ static int xdbc_start(void)
 
xdbc_trace("root hub port number %d\n", DCST_DPN(status));
 
+   xdbcp->in_ep_state = EP_RUNNING;
+   xdbcp->out_ep_state = EP_RUNNING;
+
xdbc_trace("DbC is running now, control 0x%08x\n",
readl(>xdbc_reg->control));
 
@@ -895,3 +918,353 @@ int __init early_xdbc_init(char *s)
 
return 0;
 }
+
+static void xdbc_queue_trb(struct xdbc_ring *ring,
+   u32 field1, u32 field2, u32 field3, u32 field4)
+{
+   struct xdbc_trb *trb, *link_trb;
+
+   trb = ring->enqueue;
+   trb->field[0] = cpu_to_le32(field1);
+   trb->field[1] = cpu_to_le32(field2);
+   trb->field[2] = cpu_to_le32(field3);
+   trb->field[3] = cpu_to_le32(field4);
+
+   xdbc_dbg_dump_trb(trb, "enqueue trb");
+
+   ++(ring->enqueue);
+   if (ring->enqueue >= >segment->trbs[TRBS_PER_SEGMENT - 1]) {
+   link_trb = ring->enqueue;
+   if (ring->cycle_state)
+   link_trb->field[3] |= cpu_to_le32(TRB_CYCLE);
+   else
+   link_trb->field[3] &= cpu_to_le32(~TRB_CYCLE);
+
+   ring->enqueue = ring->segment->trbs;
+   ring->cycle_state ^= 1;
+   }
+}
+
+static void xdbc_ring_doorbell(int target)
+{
+   writel(DOOR_BELL_TARGET(target), >xdbc_reg->doorbell);
+}
+
+static void xdbc_handle_port_status(struct xdbc_trb *evt_trb)
+{
+   u32 port_reg;
+
+   port_reg = readl(>xdbc_reg->portsc);
+
+   if (port_reg & PORTSC_CSC) {
+   xdbc_trace("%s: connect status change event\n", __func__);
+   writel(port_reg | PORTSC_CSC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PRC) {
+   xdbc_trace("%s: port reset change event\n", __func__);
+   writel(port_reg | PORTSC_PRC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PLC) {
+   xdbc_trace("%s: port link status change event\n", __func__);
+   writel(

[PATCH v3 10/12] usb: xhci: dbc: add handshake between debug target and host

[Lu Baolu]

After DbC setup, debug target needs to wait until tty driver and
application (e.g. mincom) on debug taget start.  Otherwise, out
messages might be ignored.

This patch adds a ping/pong mechanism between debug target and
host. Debug target will be waiting there until user presses 'Y'
or 'y' in the tty application.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 27 +++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 68a7139..b75c523 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,6 +32,9 @@
 static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
+static int early_xdbc_read(struct console *con, char *str, unsigned n);
+static void early_xdbc_write(struct console *con, const char *str, u32 n);
+
 #ifdef DBC_DEBUG
 #defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
 #defineMSG_MAX_LINE128
@@ -873,8 +876,12 @@ int __init early_xdbc_init(char *s)
 {
u32 bus = 0, dev = 0, func = 0;
unsigned long dbgp_num = 0;
+   char *ping = "Press Y to continue...\n";
+   char pong[64];
+   size_t size;
u32 offset;
int ret;
+   int retry = 20;
 
if (!early_pci_allowed())
return -EPERM;
@@ -917,6 +924,21 @@ int __init early_xdbc_init(char *s)
return ret;
}
 
+   while (retry > 0) {
+   early_xdbc_write(NULL, ping, strlen(ping));
+   size = early_xdbc_read(NULL, pong, 64);
+   if (size > 0) {
+   xdbc_trace("%s: pong message: %s\n", __func__, pong);
+   if (pong[0] == 'Y' || pong[0] == 'y')
+   break;
+   } else {
+   xdbc_trace("%s: pong message error %d\n",
+   __func__, size);
+   }
+
+   retry--;
+   }
+
return 0;
 }
 
@@ -1338,6 +1360,11 @@ int xdbc_bulk_write(const char *bytes, int size)
  * Start a bulk-in or bulk-out transfer, wait until transfer completion
  * or error. Return the count of actually transferred bytes or error.
  */
+static int early_xdbc_read(struct console *con, char *str, unsigned n)
+{
+   return xdbc_bulk_read(str, n, 0);
+}
+
 static void early_xdbc_write(struct console *con, const char *str, u32 n)
 {
int chunk, ret;
-- 
2.1.4

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[PATCH v3 08/12] usb: xhci: dbc: handle endpoint stall

[Lu Baolu]

In case of endpoint stall, software is able to detect the situation
by reading DCCTRL.HIT or DCCTRL.HOT bits. DbC follows the normal USB
framework to handle endpoint stall. When software detects endpoint
stall situation, it should wait until endpoint is recovered before
read or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 36 
 1 file changed, 36 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 8a5a51f..aaf655f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1176,6 +1176,37 @@ static int xdbc_wait_until_dbc_configured(void)
return -ETIMEDOUT;
 }
 
+static int xdbc_wait_until_epstall_cleared(bool read)
+{
+   int timeout = 0;
+
+   if (read) {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HIT)) {
+   xdbcp->in_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->in_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   } else {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HOT)) {
+   xdbcp->out_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->out_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   }
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1195,6 +1226,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EPERM;
}
 
+   if (xdbc_wait_until_epstall_cleared(read)) {
+   xdbc_trace("%s: endpoint not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v3 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu Baolu]

This patch adds a sysfs file for users to check 1) whether the debug
capability is implemented by hardware; 2) if supported, which state
does it stay at.

With a host that supports debug port, a file named "debug_port_state"
will be created under the device sysfs directory. Reading this file
will show users the state (disabled, enabled or configured) of the
debug port.

With a host that does NOT support debug port, "debug_port_state" file
won't be created.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |  23 +
 drivers/usb/host/Makefile  |   2 +-
 drivers/usb/host/xhci-ext-caps.h   |  14 ++-
 drivers/usb/host/xhci-sysfs.c  | 100 +
 drivers/usb/host/xhci.c|   4 +
 drivers/usb/host/xhci.h|   4 +
 6 files changed, 145 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 drivers/usb/host/xhci-sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd 
b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
new file mode 100644
index 000..dd3e722
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -0,0 +1,23 @@
+What:  /sys/bus/pci/drivers/xhci_hcd/.../debug_port_state
+Date:  November 2015
+KernelVersion: 4.3.0
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   This file is designed for users to check the state of a
+   USB3 debug port. On a machine which supports USB3 debug
+   port, this file will be created. Reading this file will
+   show the state (disabled, enabled or configured) of the
+   debug port. On a machine that doesn't support USB3 debug
+   port, this file doesn't exist.
+
+   The state of a debug port could be:
+   1) disabled: The debug port is not enabled and the root
+   port has been switched to xHCI host as a normal
+   root port.
+   2) enabled: The debug port is enabled. The debug port
+   has been assigned to debug capability. The debug
+   capability is able to handle the control requests
+   defined in USB3 spec.
+   3) configured: The debug port has been enumerated by the
+   debug host as a debug device. The debug port is
+   in use now.
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index e7558ab..810c304 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -12,7 +12,7 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
-xhci-hcd-y += xhci-trace.o
+xhci-hcd-y += xhci-trace.o xhci-sysfs.o
 
 xhci-plat-hcd-y := xhci-plat.o
 ifneq ($(CONFIG_USB_XHCI_MVEBU), )
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 9fe3225..12c87e5 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -49,8 +49,15 @@
 #define XHCI_EXT_CAPS_PM   3
 #define XHCI_EXT_CAPS_VIRT 4
 #define XHCI_EXT_CAPS_ROUTE5
-/* IDs 6-9 reserved */
+#define XHCI_EXT_CAPS_LOCALMEM 6
+/* IDs 7-9 reserved */
 #define XHCI_EXT_CAPS_DEBUG10
+/* IDs 192-255 vendor specific */
+#define XHCI_EXT_CAPS_VEN_START192
+#define XHCI_EXT_CAPS_VEN_END  255
+#define XHCI_EXT_CAPS_VENDOR(p)(((p) >= XHCI_EXT_CAPS_VEN_START) && \
+   ((p) <= XHCI_EXT_CAPS_VEN_END))
+#define XHCI_EXT_MAX_CAPID XHCI_EXT_CAPS_VEN_END
 /* USB Legacy Support Capability - section 7.1.1 */
 #define XHCI_HC_BIOS_OWNED (1 << 16)
 #define XHCI_HC_OS_OWNED   (1 << 24)
@@ -73,6 +80,11 @@
 #define XHCI_HLC   (1 << 19)
 #define XHCI_BLC   (1 << 20)
 
+/* Debug capability - section 7.6.8 */
+#define XHCI_DBC_DCCTRL0x20
+#define XHCI_DBC_DCCTRL_DCR(1 << 0)
+#defineXHCI_DBC_DCCTRL_DCE (1 << 31)
+
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/
 #define XHCI_CMD_RUN   (1 << 0)
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 000..0192ac4
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,100 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by th

[PATCH v3 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in sysfs, through which users can check
whether the debug capability is supported by a specific host controller,
and the hardware state.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.

Change log:
v1->v2:
(1) Patch 1 re-implemented. "debugfs" has been replaced with sysfs.
The scope reduced from all extended capabilities to debug port
specific.
(2) Patch 11 changed. Removed unnecessary .bulk_out_size setting.

v2->v3:
(1) Patch 11 got acked by Johan Hovold.

Lu Baolu (12):
  usb: xhci: add sysfs file for xHCI debug port
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: xhci: dbc: probe and setup xhci debug capability
  usb: xhci: dbc: add support for Intel xHCI dbc quirk
  usb: xhci: dbc: add debug buffer
  usb: xhci: dbc: add bulk out and bulk in interfaces
  usb: xhci: dbc: handle dbc-configured exit
  usb: xhci: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: xhci: dbc: add handshake between debug target and host
  usb: serial: usb_debug: add support for dbc debug device
  usb: doc: add document for xHCI DbC driver

 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |   23 +
 Documentation/kernel-parameters.txt|1 +
 Documentation/usb/xhci-dbc.txt |  325 +
 MAINTAINERS|8 +
 arch/x86/Kconfig.debug |   12 +
 arch/x86/include/asm/fixmap.h  |4 +
 arch/x86/kernel/early_printk.c |5 +
 drivers/usb/early/Makefile |1 +
 drivers/usb/early/xhci-dbc.c   | 1407 
 drivers/usb/host/Makefile  |2 +-
 drivers/usb/host/xhci-ext-caps.h   |   14 +-
 drivers/usb/host/xhci-sysfs.c  |  100 ++
 drivers/usb/host/xhci.c|4 +
 drivers/usb/host/xhci.h|4 +
 drivers/usb/serial/usb_debug.c |   28 +-
 include/linux/usb/xhci-dbc.h   |  224 
 16 files changed, 2157 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 drivers/usb/host/xhci-sysfs.c
 create mode 100644 include/linux/usb/xhci-dbc.h

-- 
2.1.4

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Re: [PATCH 01/12] usb: xhci: expose xhci extended capabilities via debugfs

[Lu, Baolu]

On 10/30/2015 10:45 PM, Greg Kroah-Hartman wrote:

On Fri, Oct 30, 2015 at 08:09:17PM +0800, Lu, Baolu wrote:


On 10/28/2015 08:40 PM, Greg Kroah-Hartman wrote:

+static const char *get_extcap_desc(u32 cap_id)

+{
+   switch (cap_id) {
+   case XHCI_EXT_CAPS_LEGACY:
+   return "USB Legacy Support";
+   case XHCI_EXT_CAPS_PROTOCOL:
+   return "Supported Protocol";
+   case XHCI_EXT_CAPS_PM:
+   return "Extended Power Management";
+   case XHCI_EXT_CAPS_VIRT:
+   return "I/O Virtualization (xHCI-IOV)";
+   case XHCI_EXT_CAPS_ROUTE:
+   return "Message Interrupt";
+   case XHCI_EXT_CAPS_LOCALMEM:
+   return "Local Memory";
+   case XHCI_EXT_CAPS_DEBUG:
+   return "USB Debug Capability";

This is a lot more stuff than just debug port, it should be in sysfs
as individual files, not one big one that you somehow have to parse in
order to determine this information.


Hi Greg,

It's hard to put each extended capability into a individual sysfs file.

Agreed.


The extended capabilities are optional. One extended capability
might be supported in one hardware, but not in another. Also,
there are many "vendor defined" capabilities (ID range 192-255).
The vendor defined capabilities are not defined in xhci spec and
they could be used by the hardware vendor for various purposes.

The purpose of this patch is to let user know what kind of extended
capabilities does a host controller supported. For example, on
one of my develop machines, it prints,

@addr(virt)CAP_IDDescription
@c90001c8800002Supported Protocol
@c90001c8802002Supported Protocol
@c90001c88070c0Vendor Defined
@c90001c8846c01USB Legacy Support
@c90001c884f4c6Vendor Defined
@c90001c88500c7Vendor Defined
@c90001c88600c2Vendor Defined
@c90001c887000aUSB Debug Capability
@c90001c88740c3Vendor Defined
@c90001c88800c4Vendor Defined
@c90001c88900c5Vendor Defined

With this output I know that "USB Debug Capability" is supported
in my machine.

First off, why are you printing the address out?  Userspace never needs
to see that.  Why not just iterate through the protocols and export the
information as different files:
protocol_XX
and if the file is present or not describes if the hardware supports it
or not.

The issue with debugfs is that it is not enabled on all systems, and
only can be read by the root user, so it is hard for people to find this
information out if they want to do normal things with the hardware.


I agree with you that we should do this thru sysfs, not debugfs.



But, if this really is only a debug thing, then it can say a debugfs
file, but realize that almost no one will be able to see it (and even
then, don't export the kernel addresses of the hardware.)


I realized that not all extended capabilities are valuable to users.

As far as I can see, debug capability (hw implements USB3 debug
port) is one that users should be interested at. Another one that
could be valuable is USB 3.1 speed protocol (root ports that support
USB 3.1 enhanced super speed).

For this time being, I will only implement sysfs node for debug
port. I will make a separated patch for USB 3.1 speed port after
I have Mathias' opinion.



thanks,

greg k-h


Thanks,
Baolu


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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

Thanks for the information. I will let you know if I have anything.

Thanks,
Baolu

On 11/01/2015 04:20 AM, Steinar H. Gunderson wrote:

On Wed, Oct 21, 2015 at 09:49:16AM +0800, Lu, Baolu wrote:

I could spend some time on this issue a week later.
I'd like to check whether there is any bugs in the driver itself.
Otherwise, blacklist this specific device for LPM.

I don't know if anything happened here, but if you need information for a
blacklist, the two devices I've tested (which both have this issue) are:

  - 1edb:bd3b (Blackmagic Design Intensity Shuttle)
  - 1edb:bd4f (Blackmagic Design UltraStudio SDI)

/* Steinar */


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[PATCH v2 10/12] usb: xhci: dbc: add handshake between debug target and host

[Lu Baolu]

After DbC setup, debug target needs to wait until tty driver and
application (e.g. mincom) on debug taget start.  Otherwise, out
messages might be ignored.

This patch adds a ping/pong mechanism between debug target and
host. Debug target will be waiting there until user presses 'Y'
or 'y' in the tty application.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 27 +++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 68a7139..b75c523 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,6 +32,9 @@
 static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
+static int early_xdbc_read(struct console *con, char *str, unsigned n);
+static void early_xdbc_write(struct console *con, const char *str, u32 n);
+
 #ifdef DBC_DEBUG
 #defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
 #defineMSG_MAX_LINE128
@@ -873,8 +876,12 @@ int __init early_xdbc_init(char *s)
 {
u32 bus = 0, dev = 0, func = 0;
unsigned long dbgp_num = 0;
+   char *ping = "Press Y to continue...\n";
+   char pong[64];
+   size_t size;
u32 offset;
int ret;
+   int retry = 20;
 
if (!early_pci_allowed())
return -EPERM;
@@ -917,6 +924,21 @@ int __init early_xdbc_init(char *s)
return ret;
}
 
+   while (retry > 0) {
+   early_xdbc_write(NULL, ping, strlen(ping));
+   size = early_xdbc_read(NULL, pong, 64);
+   if (size > 0) {
+   xdbc_trace("%s: pong message: %s\n", __func__, pong);
+   if (pong[0] == 'Y' || pong[0] == 'y')
+   break;
+   } else {
+   xdbc_trace("%s: pong message error %d\n",
+   __func__, size);
+   }
+
+   retry--;
+   }
+
return 0;
 }
 
@@ -1338,6 +1360,11 @@ int xdbc_bulk_write(const char *bytes, int size)
  * Start a bulk-in or bulk-out transfer, wait until transfer completion
  * or error. Return the count of actually transferred bytes or error.
  */
+static int early_xdbc_read(struct console *con, char *str, unsigned n)
+{
+   return xdbc_bulk_read(str, n, 0);
+}
+
 static void early_xdbc_write(struct console *con, const char *str, u32 n)
 {
int chunk, ret;
-- 
2.1.4

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[PATCH v2 08/12] usb: xhci: dbc: handle endpoint stall

[Lu Baolu]

In case of endpoint stall, software is able to detect the situation
by reading DCCTRL.HIT or DCCTRL.HOT bits. DbC follows the normal USB
framework to handle endpoint stall. When software detects endpoint
stall situation, it should wait until endpoint is recovered before
read or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 36 
 1 file changed, 36 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 8a5a51f..aaf655f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1176,6 +1176,37 @@ static int xdbc_wait_until_dbc_configured(void)
return -ETIMEDOUT;
 }
 
+static int xdbc_wait_until_epstall_cleared(bool read)
+{
+   int timeout = 0;
+
+   if (read) {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HIT)) {
+   xdbcp->in_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->in_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   } else {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HOT)) {
+   xdbcp->out_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->out_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   }
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1195,6 +1226,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EPERM;
}
 
+   if (xdbc_wait_until_epstall_cleared(read)) {
+   xdbc_trace("%s: endpoint not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v2 09/12] x86: early_printk: add USB3 debug port earlyprintk support

[Lu Baolu]

Add support for early printk by writing debug messages to the USB3
debug port. Users can use this type of early printk by specifying
kernel parameter of "earlyprintk=xdbc". This gives users a chance
of providing debug output.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/kernel-parameters.txt |  1 +
 arch/x86/kernel/early_printk.c  |  5 +
 drivers/usb/early/xhci-dbc.c| 43 +
 include/linux/usb/xhci-dbc.h|  5 +
 4 files changed, 54 insertions(+)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index 22a4b68..b65b07f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1032,6 +1032,7 @@ bytes respectively. Such letter suffixes can also be 
entirely omitted.
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
earlyprintk=pciserial,bus:device.function[,baudrate]
+   earlyprintk=xdbc[xhciController#]
 
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index eec40f5..5341a16 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -373,6 +374,10 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
early_console_register(_dbgp_console, keep);
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   if (!strncmp(buf, "xdbc", 4) && !early_xdbc_init(buf + 4))
+   early_console_register(_xdbc_console, keep);
+#endif
 #ifdef CONFIG_HVC_XEN
if (!strncmp(buf, "xen", 3))
early_console_register(_console, keep);
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index aaf655f..68a7139 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -10,6 +10,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include 
 #include 
 #include 
 #include 
@@ -1332,3 +1333,45 @@ int xdbc_bulk_write(const char *bytes, int size)
 
return ret;
 }
+
+/*
+ * Start a bulk-in or bulk-out transfer, wait until transfer completion
+ * or error. Return the count of actually transferred bytes or error.
+ */
+static void early_xdbc_write(struct console *con, const char *str, u32 n)
+{
+   int chunk, ret;
+   static char buf[XDBC_MAX_PACKET];
+   int use_cr = 0;
+
+   if (!xdbcp->xdbc_reg)
+   return;
+   memset(buf, 0, XDBC_MAX_PACKET);
+   while (n > 0) {
+   for (chunk = 0; chunk < XDBC_MAX_PACKET && n > 0;
+str++, chunk++, n--) {
+   if (!use_cr && *str == '\n') {
+   use_cr = 1;
+   buf[chunk] = '\r';
+   str--;
+   n++;
+   continue;
+   }
+   if (use_cr)
+   use_cr = 0;
+   buf[chunk] = *str;
+   }
+   if (chunk > 0) {
+   ret = xdbc_bulk_write(buf, chunk);
+   if (ret < 0)
+   break;
+   }
+   }
+}
+
+struct console early_xdbc_console = {
+   .name = "earlyxdbc",
+   .write =early_xdbc_write,
+   .flags =CON_PRINTBUFFER,
+   .index =-1,
+};
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 289ba58..a556eb8 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -216,4 +216,9 @@ struct xdbc_state {
 #definexdbc_read64(regs)   xhci_read_64(NULL, (regs))
 #definexdbc_write64(val, regs) xhci_write_64(NULL, (val), (regs))
 
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+extern int early_xdbc_init(char *s);
+extern struct console early_xdbc_console;
+#endif /* CONFIG_EARLY_PRINTK_XDBC */
+
 #endif /* __LINUX_XHCI_DBC_H */
-- 
2.1.4

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[PATCH v2 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in sysfs, through which users can check
whether the debug capability is supported by a specific host controller,
and the hardware state.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.

Change log:
v1->v2:
(1) Patch 1 re-implemented. "debugfs" has been replaced with sysfs.
The scope reduced from all extended capabilities to debug port
specific.
(2) Patch 11 changed. Removed unnecessary .bulk_out_size setting.

Lu Baolu (12):
  usb: xhci: add sysfs file for xHCI debug port
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: xhci: dbc: probe and setup xhci debug capability
  usb: xhci: dbc: add support for Intel xHCI dbc quirk
  usb: xhci: dbc: add debug buffer
  usb: xhci: dbc: add bulk out and bulk in interfaces
  usb: xhci: dbc: handle dbc-configured exit
  usb: xhci: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: xhci: dbc: add handshake between debug target and host
  usb: serial: usb_debug: add support for dbc debug device
  usb: doc: add document for xHCI DbC driver

 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |   23 +
 Documentation/kernel-parameters.txt|1 +
 Documentation/usb/xhci-dbc.txt |  325 +
 MAINTAINERS|8 +
 arch/x86/Kconfig.debug |   12 +
 arch/x86/include/asm/fixmap.h  |4 +
 arch/x86/kernel/early_printk.c |5 +
 drivers/usb/early/Makefile |1 +
 drivers/usb/early/xhci-dbc.c   | 1407 
 drivers/usb/host/Makefile  |2 +-
 drivers/usb/host/xhci-ext-caps.h   |   14 +-
 drivers/usb/host/xhci-sysfs.c  |  100 ++
 drivers/usb/host/xhci.c|4 +
 drivers/usb/host/xhci.h|4 +
 drivers/usb/serial/usb_debug.c |   28 +-
 include/linux/usb/xhci-dbc.h   |  224 
 16 files changed, 2157 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 drivers/usb/host/xhci-sysfs.c
 create mode 100644 include/linux/usb/xhci-dbc.h

-- 
2.1.4

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[PATCH v2 06/12] usb: xhci: dbc: add bulk out and bulk in interfaces

[Lu Baolu]

This patch adds interfaces for bulk out and bulk in ops. These
interfaces could be used to implement early printk bootconsole
or hook to various system debuggers.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 373 +++
 include/linux/usb/xhci-dbc.h |  30 
 2 files changed, 403 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index b36a527..f51daa4 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -219,11 +219,21 @@ static void xdbc_dbg_dump_data(char *str)
xdbc_dbg_dump_string("String Descriptor:");
 }
 
+static void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str)
+{
+   xdbc_trace("DBC trb: %s\n", str);
+   xdbc_trace("@%016llx %08x %08x %08x %08x\n", (u64)__pa(trb),
+   le32_to_cpu(trb->field[0]),
+   le32_to_cpu(trb->field[1]),
+   le32_to_cpu(trb->field[2]),
+   le32_to_cpu(trb->field[3]));
+}
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
 static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
+static inline void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str) { }
 #endif /* DBC_DEBUG */
 
 /*
@@ -334,6 +344,7 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
static char in_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char out_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char table_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+   static char bulk_buf_page[PAGE_SIZE] __aligned(PAGE_SIZE);
 
switch (type) {
case XDBC_PAGE_EVENT:
@@ -348,6 +359,9 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
case XDBC_PAGE_TABLE:
virt = (void *)table_page;
break;
+   case XDBC_PAGE_BUFFER:
+   virt = (void *)bulk_buf_page;
+   break;
default:
return NULL;
}
@@ -707,6 +721,12 @@ static int xdbc_mem_init(void)
dev_info = cpu_to_le32((XDBC_DEVICE_REV << 16) | XDBC_PRODUCT_ID);
writel(dev_info, >xdbc_reg->devinfo2);
 
+   /* get and store the transfer buffer */
+   xdbcp->out_buf = xdbc_get_page(>out_dma,
+   XDBC_PAGE_BUFFER);
+   xdbcp->in_buf = xdbcp->out_buf + XDBC_MAX_PACKET;
+   xdbcp->in_dma = xdbcp->out_dma + XDBC_MAX_PACKET;
+
return 0;
 }
 
@@ -802,6 +822,9 @@ static int xdbc_start(void)
 
xdbc_trace("root hub port number %d\n", DCST_DPN(status));
 
+   xdbcp->in_ep_state = EP_RUNNING;
+   xdbcp->out_ep_state = EP_RUNNING;
+
xdbc_trace("DbC is running now, control 0x%08x\n",
readl(>xdbc_reg->control));
 
@@ -895,3 +918,353 @@ int __init early_xdbc_init(char *s)
 
return 0;
 }
+
+static void xdbc_queue_trb(struct xdbc_ring *ring,
+   u32 field1, u32 field2, u32 field3, u32 field4)
+{
+   struct xdbc_trb *trb, *link_trb;
+
+   trb = ring->enqueue;
+   trb->field[0] = cpu_to_le32(field1);
+   trb->field[1] = cpu_to_le32(field2);
+   trb->field[2] = cpu_to_le32(field3);
+   trb->field[3] = cpu_to_le32(field4);
+
+   xdbc_dbg_dump_trb(trb, "enqueue trb");
+
+   ++(ring->enqueue);
+   if (ring->enqueue >= >segment->trbs[TRBS_PER_SEGMENT - 1]) {
+   link_trb = ring->enqueue;
+   if (ring->cycle_state)
+   link_trb->field[3] |= cpu_to_le32(TRB_CYCLE);
+   else
+   link_trb->field[3] &= cpu_to_le32(~TRB_CYCLE);
+
+   ring->enqueue = ring->segment->trbs;
+   ring->cycle_state ^= 1;
+   }
+}
+
+static void xdbc_ring_doorbell(int target)
+{
+   writel(DOOR_BELL_TARGET(target), >xdbc_reg->doorbell);
+}
+
+static void xdbc_handle_port_status(struct xdbc_trb *evt_trb)
+{
+   u32 port_reg;
+
+   port_reg = readl(>xdbc_reg->portsc);
+
+   if (port_reg & PORTSC_CSC) {
+   xdbc_trace("%s: connect status change event\n", __func__);
+   writel(port_reg | PORTSC_CSC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PRC) {
+   xdbc_trace("%s: port reset change event\n", __func__);
+   writel(port_reg | PORTSC_PRC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PLC) {
+   xdbc_trace("%s: port link status change event\n", __func__);
+   writel(

[PATCH v2 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk

[Lu Baolu]

On Intel platform, if the debug target is connected with debug
host, enabling DCE bit in command register leads to a hung bus
state. In the hung state, the host system will not see a port
connected status bit set. Hence debug target fails to be probed.

The state could be resolved by performing a port reset to the
debug port from the host xHCI. This patch introduces this work
around.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 52 
 include/linux/usb/xhci-dbc.h |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 22a1de9..6b23f09 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -255,6 +255,8 @@ static void __iomem *xdbc_map_pci_mmio(u32 bus,
xdbcp->bar = bar;
xdbcp->xhci_base = base;
xdbcp->xhci_length = sz64;
+   xdbcp->vendor = read_pci_config_16(bus, dev, func, PCI_VENDOR_ID);
+   xdbcp->device = read_pci_config_16(bus, dev, func, PCI_DEVICE_ID);
 
if (length)
*length = sz64;
@@ -651,6 +653,52 @@ static int xdbc_mem_init(void)
return 0;
 }
 
+static void xdbc_reset_debug_port_callback(int cap_offset, void *data)
+{
+   u8 major;
+   u32 val, port_offset, port_count;
+   u32 cap_length;
+   void __iomem *ops_reg;
+   void __iomem *portsc;
+   int i;
+
+   val = readl(xdbcp->xhci_base + cap_offset);
+   major = (u8) XHCI_EXT_PORT_MAJOR(val);
+
+   /* only reset super-speed port */
+   if (major != 0x3)
+   return;
+
+   val = readl(xdbcp->xhci_base + cap_offset + 8);
+   port_offset = XHCI_EXT_PORT_OFF(val);
+   port_count = XHCI_EXT_PORT_COUNT(val);
+   xdbc_trace("Extcap Port offset %d count %d\n",
+   port_offset, port_count);
+
+   cap_length = readl(xdbcp->xhci_base) & 0xff;
+   ops_reg = xdbcp->xhci_base + cap_length;
+
+   port_offset--;
+   for (i = port_offset; i < (port_offset + port_count); i++) {
+   portsc = ops_reg + 0x400 + i * 0x10;
+   val = readl(portsc);
+   /* reset the port if CCS bit is cleared */
+   if (!(val & 0x1))
+   writel(val | (1 << 4), portsc);
+   }
+}
+
+static void xdbc_reset_debug_port(void)
+{
+   xdbc_walk_excap(xdbcp->bus,
+   xdbcp->dev,
+   xdbcp->func,
+   XHCI_EXT_CAPS_PROTOCOL,
+   false,
+   xdbc_reset_debug_port_callback,
+   NULL);
+}
+
 /*
  * xdbc_start: start DbC
  *
@@ -669,6 +717,10 @@ static int xdbc_start(void)
return -ENODEV;
}
 
+   /* reset port to avoid bus hang */
+   if (xdbcp->vendor == PCI_VENDOR_ID_INTEL)
+   xdbc_reset_debug_port();
+
/* wait for port connection */
if (handshake(>xdbc_reg->portsc, PORTSC_CCS,
PORTSC_CCS, 500, 100) < 0) {
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 153fb87..fc0ef9a 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -128,6 +128,8 @@ struct xdbc_state {
u32 dev;
u32 func;
u8  bar;
+   u16 vendor;
+   u16 device;
void __iomem*xhci_base;
size_t  xhci_length;
 #defineXDBC_PCI_MAX_BUSES  256
-- 
2.1.4

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[PATCH v2 05/12] usb: xhci: dbc: add debug buffer

[Lu Baolu]

"printk" is not suitable for dbc debugging especially when console
is in usage. This patch adds a debug buffer in dbc driver and puts
the debug messages in this local buffer. The debug buffer could be
dumped whenever the console is not in use. This part of code will
not be visible unless DBC_DEBUG is defined.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 62 ++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 6b23f09..b36a527 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,8 +32,64 @@ static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
 #ifdef DBC_DEBUG
-/* place holder */
-#definexdbc_trace  printk
+#defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
+#defineMSG_MAX_LINE128
+static char xdbc_debug_buf[XDBC_DEBUG_BUF_SIZE];
+static void xdbc_trace(const char *fmt, ...)
+{
+   int i, size;
+   va_list args;
+   static int pos;
+   char temp_buf[MSG_MAX_LINE];
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   return;
+
+   memset(temp_buf, 0, MSG_MAX_LINE);
+   va_start(args, fmt);
+   vsnprintf(temp_buf, MSG_MAX_LINE - 1, fmt, args);
+   va_end(args);
+
+   i = 0;
+   size = strlen(temp_buf);
+   while (i < size) {
+   xdbc_debug_buf[pos] = temp_buf[i];
+   pos++;
+   i++;
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   break;
+   }
+}
+
+static void xdbc_dump_debug_buffer(void)
+{
+   int index = 0;
+   int count = 0;
+   char dump_buf[MSG_MAX_LINE];
+
+   xdbc_trace("The end of DbC trace buffer\n");
+   pr_notice("DBC debug buffer:\n");
+   memset(dump_buf, 0, MSG_MAX_LINE);
+
+   while (index < XDBC_DEBUG_BUF_SIZE) {
+   if (!xdbc_debug_buf[index])
+   break;
+
+   if (xdbc_debug_buf[index] == '\n' ||
+   count >= MSG_MAX_LINE - 1) {
+   pr_notice("DBC: @%08x %s\n", index, dump_buf);
+   memset(dump_buf, 0, MSG_MAX_LINE);
+   count = 0;
+   } else {
+   dump_buf[count] = xdbc_debug_buf[index];
+   count++;
+   }
+
+   index++;
+   }
+}
+
 static void xdbc_dbg_dump_regs(char *str)
 {
if (!xdbcp->xdbc_reg) {
@@ -165,6 +221,7 @@ static void xdbc_dbg_dump_data(char *str)
 
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
+static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
 #endif /* DBC_DEBUG */
@@ -832,6 +889,7 @@ int __init early_xdbc_init(char *s)
pr_notice("failed to setup xHCI DbC connection\n");
xdbcp->xhci_base = NULL;
xdbcp->xdbc_reg = NULL;
+   xdbc_dump_debug_buffer();
return ret;
}
 
-- 
2.1.4

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[PATCH v2 12/12] usb: doc: add document for xHCI DbC driver

[Lu Baolu]

Add Documentation/usb/xhci-dbc.txt. This document includes
development status and user guide for USB3 debug port.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/usb/xhci-dbc.txt | 325 +
 MAINTAINERS|   1 +
 drivers/usb/early/xhci-dbc.c   |   3 +
 3 files changed, 329 insertions(+)
 create mode 100644 Documentation/usb/xhci-dbc.txt

diff --git a/Documentation/usb/xhci-dbc.txt b/Documentation/usb/xhci-dbc.txt
new file mode 100644
index 000..441b40c
--- /dev/null
+++ b/Documentation/usb/xhci-dbc.txt
@@ -0,0 +1,325 @@
+xHCI debug capability driver
+
+         Lu Baolu <baolu...@linux.intel.com>
+
+Last-updated: September 2015
+
+
+   Contents:
+   -
+   * What is xHCI DbC?
+   * Debug topologies
+   * Debug stacks
+   * Port Multiplexing
+   * Hardware initialization
+   * External reset
+   * Port reset
+   * Interrupt/DMA/Memory during early boot
+   * Endpoint STALL
+   * Debug device information
+   * How to use DbC early printk?
+   * Limitations
+
+   What is xHCI DbC?
+   -
+
+The xHCI Debugging Capability defined in section 7.6 of xHCI spec 1.1
+provides an optional functionality that enables low-level system debug
+over USB. It provides a means of connecting two systems where one system
+is a Debug Host and the other a Debug Target (System Under Test). The
+Debug Capability provides an interface that is completely independent
+of the xHCI interface. A Debug Target enumerates as a USB debug device
+to the Debug Host, allowing a Debug Host to access a Debug Target through
+the standard USB software stack.
+
+   Debug topologies
+   
+
+Multiple Debug Targets may be attached to a single Debug Host. Debug
+Targets may be connected to any downstream facing port below a Debug
+Host (i.e. anywhere in the fabric, root port or external hub puts).
+A Debug Target may only connect to a Debug Host through a Root Hub port
+of the target. That means connection of a Debug Target to a Debug Host
+through the ports of an external hub is not supported.
+
+Below is a typical connection between Debug Host and Debug target. Two
+Debug targets are connected to a single Debug host.
+
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+  || |
+  ||_|
+  |_
+|
+ ___|
+|   HUB  |  |  Debug Target  |
+||  ||
+| Superspeed hub |  |  xHC with DbC  |
+||  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+   Debug stacks
+   
+
+Below is a software stack diagram of both Debug Host and Debug Target.
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|   debug App|  ||
+||  | system debug   |
+|   usb_debug|  | hooks  |
+||  ||
+|usbcore |  ||
+||  |debug capability|
+|xhci_hcd|  | driver |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+
+   Port Multiplexing
+   -
+
+A debug port is always multiplexed with the first xHCI root hub port.
+Whenever debug capability is supported and enabled, and the first root
+hub port is detected to be connected to a downstream super-speed port
+of a Debug Host, the r

[PATCH v2 03/12] usb: xhci: dbc: probe and setup xhci debug capability

[Lu Baolu]

xHCI debug capability (DbC) is an optional functionality provided
by an xHCI host controller. Software learns this capability by
walking through the extended capability list in mmio of the host.

This patch introduces the code to probe and initialize the debug
capability hardware during early boot. With hardware initialization
done, the debug target (system under debug which has DbC enabled)
will present a debug device through the debug port. The debug device
is fully compliant with the USB framework and provides the equivalent
of a very high performance (USB3) full-duplex serial link between the
debug host and target.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 MAINTAINERS  |   7 +
 arch/x86/Kconfig.debug   |  12 +
 drivers/usb/early/Makefile   |   1 +
 drivers/usb/early/xhci-dbc.c | 787 +++
 include/linux/usb/xhci-dbc.h | 187 ++
 5 files changed, 994 insertions(+)
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 0425167..585a369 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11040,6 +11040,13 @@ S: Supported
 F: drivers/usb/host/xhci*
 F: drivers/usb/host/pci-quirks*
 
+USB XHCI DEBUG PORT
+M:     Lu Baolu <baolu...@linux.intel.com>
+L: linux-usb@vger.kernel.org
+S: Supported
+F: drivers/usb/early/xhci-dbc.c
+F: include/linux/usb/xhci-dbc.h
+
 USB ZD1201 DRIVER
 L: linux-wirel...@vger.kernel.org
 W: http://linux-lc100020.sourceforge.net
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index d8c0d32..8d95abd 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -65,6 +65,18 @@ config EARLY_PRINTK_EFI
  This is useful for kernel debugging when your machine crashes very
  early before the console code is initialized.
 
+config EARLY_PRINTK_XDBC
+   bool "Early printk via xHCI debug port"
+   depends on EARLY_PRINTK && PCI
+   ---help---
+ Write kernel log output directly into the xHCI debug port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash.
+
 config X86_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
diff --git a/drivers/usb/early/Makefile b/drivers/usb/early/Makefile
index 24bbe51..2db5906 100644
--- a/drivers/usb/early/Makefile
+++ b/drivers/usb/early/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_EARLY_PRINTK_DBGP) += ehci-dbgp.o
+obj-$(CONFIG_EARLY_PRINTK_XDBC) += xhci-dbc.o
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
new file mode 100644
index 000..22a1de9
--- /dev/null
+++ b/drivers/usb/early/xhci-dbc.c
@@ -0,0 +1,787 @@
+/**
+ * xhci-dbc.c - xHCI debug capability driver
+ *
+ * Copyright (C) 2015 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ * Some code shared with EHCI debug port and xHCI driver.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include "../host/xhci.h"
+
+#defineXDBC_PROTOCOL   1   /* GNU Remote Debug Command Set 
*/
+#defineXDBC_VENDOR_ID  0x1d6b  /* Linux Foundation 0x1d6b */
+#defineXDBC_PRODUCT_ID 0x0004  /* __le16 idProduct; device 
0004 */
+#defineXDBC_DEVICE_REV 0x0010  /* 0.10 */
+
+static struct xdbc_state xdbc_stat;
+static struct xdbc_state *xdbcp = _stat;
+
+#ifdef DBC_DEBUG
+/* place holder */
+#definexdbc_trace  printk
+static void xdbc_dbg_dump_regs(char *str)
+{
+   if (!xdbcp->xdbc_reg) {
+   xdbc_trace("register not mapped\n");
+   return;
+   }
+
+   xdbc_trace("XDBC registers: %s\n", str);
+   xdbc_trace("  Capability: %08x\n",
+   readl(>xdbc_reg->capability));
+   xdbc_trace("  Door bell: %08x\n",
+   readl(>xdbc_reg->doorbell));
+   xdbc_trace("  Event Ring Segment Table Size: %08x\n",
+   readl(>xdbc_reg->ersts));
+   xdbc_trace("  Event Ring Segment Table Base Address: %16llx\n",
+   xdbc_read64(>xdbc_reg->erstba));
+   xdbc_trace("  Event Ring Dequeue Pointer: %16llx\n",
+   xdbc_read64(>xdbc_reg->erdp));
+   xdbc

[PATCH v2 02/12] x86: fixmap: add permanent fixmap for xhci debug port

[Lu Baolu]

xHCI compatible USB3 host controller may provide debug capability
which enables low-level system debug over USB. In order to probing
this debug capability, Linux kernel needs to map and access the
mmio of the host controller during early boot.

This patch adds permenent fixmap pages in fixed_addresses table for
xHCI mmio access.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 arch/x86/include/asm/fixmap.h | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index f80d700..fbf452f 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -82,6 +82,10 @@ enum fixed_addresses {
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
FIX_OHCI1394_BASE,
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   FIX_XDBC_BASE,
+   FIX_XDBC_END = FIX_XDBC_BASE + 15,
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
 #endif
-- 
2.1.4

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[PATCH v2 07/12] usb: xhci: dbc: handle dbc-configured exit

[Lu Baolu]

DbC might exit configured state in some cases (refer to 7.6.4.4 in
xHCI spec 1.1). Software needs detect and clear this situation by
clearing DCCTRL.DCR and wait until the DbC configured before read
or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 28 
 1 file changed, 28 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index f51daa4..8a5a51f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1153,6 +1153,29 @@ static int xdbc_wait_until_bulk_done(struct xdbc_trb 
*trb, int loops)
return -EIO;
 }
 
+static int xdbc_wait_until_dbc_configured(void)
+{
+   int timeout = 0;
+   u32 reg;
+
+   /* Port exits configured state */
+   reg = readl(>xdbc_reg->control);
+   if (!(reg & CTRL_DRC))
+   return 0;
+
+   /* clear run change bit (RW1C) */
+   writel(reg | CTRL_DRC, >xdbc_reg->control);
+
+   do {
+   if (readl(>xdbc_reg->control) & CTRL_DCR)
+   return 0;
+
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1167,6 +1190,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EINVAL;
}
 
+   if (xdbc_wait_until_dbc_configured()) {
+   xdbc_trace("%s: hardware not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v2 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu Baolu]

This patch adds a sysfs file for users to check 1) whether the debug
capability is implemented by hardware; 2) if supported, which state
does it stay at.

With a host that supports debug port, a file named "debug_port_state"
will be created under the device sysfs directory. Reading this file
will show users the state (disabled, enabled or configured) of the
debug port.

With a host that does NOT support debug port, "debug_port_state" file
won't be created.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |  23 +
 drivers/usb/host/Makefile  |   2 +-
 drivers/usb/host/xhci-ext-caps.h   |  14 ++-
 drivers/usb/host/xhci-sysfs.c  | 100 +
 drivers/usb/host/xhci.c|   4 +
 drivers/usb/host/xhci.h|   4 +
 6 files changed, 145 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 drivers/usb/host/xhci-sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd 
b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
new file mode 100644
index 000..dd3e722
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -0,0 +1,23 @@
+What:  /sys/bus/pci/drivers/xhci_hcd/.../debug_port_state
+Date:  November 2015
+KernelVersion: 4.3.0
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   This file is designed for users to check the state of a
+   USB3 debug port. On a machine which supports USB3 debug
+   port, this file will be created. Reading this file will
+   show the state (disabled, enabled or configured) of the
+   debug port. On a machine that doesn't support USB3 debug
+   port, this file doesn't exist.
+
+   The state of a debug port could be:
+   1) disabled: The debug port is not enabled and the root
+   port has been switched to xHCI host as a normal
+   root port.
+   2) enabled: The debug port is enabled. The debug port
+   has been assigned to debug capability. The debug
+   capability is able to handle the control requests
+   defined in USB3 spec.
+   3) configured: The debug port has been enumerated by the
+   debug host as a debug device. The debug port is
+   in use now.
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index e7558ab..810c304 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -12,7 +12,7 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
-xhci-hcd-y += xhci-trace.o
+xhci-hcd-y += xhci-trace.o xhci-sysfs.o
 
 xhci-plat-hcd-y := xhci-plat.o
 ifneq ($(CONFIG_USB_XHCI_MVEBU), )
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 9fe3225..12c87e5 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -49,8 +49,15 @@
 #define XHCI_EXT_CAPS_PM   3
 #define XHCI_EXT_CAPS_VIRT 4
 #define XHCI_EXT_CAPS_ROUTE5
-/* IDs 6-9 reserved */
+#define XHCI_EXT_CAPS_LOCALMEM 6
+/* IDs 7-9 reserved */
 #define XHCI_EXT_CAPS_DEBUG10
+/* IDs 192-255 vendor specific */
+#define XHCI_EXT_CAPS_VEN_START192
+#define XHCI_EXT_CAPS_VEN_END  255
+#define XHCI_EXT_CAPS_VENDOR(p)(((p) >= XHCI_EXT_CAPS_VEN_START) && \
+   ((p) <= XHCI_EXT_CAPS_VEN_END))
+#define XHCI_EXT_MAX_CAPID XHCI_EXT_CAPS_VEN_END
 /* USB Legacy Support Capability - section 7.1.1 */
 #define XHCI_HC_BIOS_OWNED (1 << 16)
 #define XHCI_HC_OS_OWNED   (1 << 24)
@@ -73,6 +80,11 @@
 #define XHCI_HLC   (1 << 19)
 #define XHCI_BLC   (1 << 20)
 
+/* Debug capability - section 7.6.8 */
+#define XHCI_DBC_DCCTRL0x20
+#define XHCI_DBC_DCCTRL_DCR(1 << 0)
+#defineXHCI_DBC_DCCTRL_DCE (1 << 31)
+
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/
 #define XHCI_CMD_RUN   (1 << 0)
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 000..0192ac4
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,100 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by th

[PATCH v2 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu Baolu]

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/serial/usb_debug.c | 28 +---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..92f7e5c 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
 };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);
 
 /* This HW really does not support a serial break, so one will be
  * emulated when ever the break state is set to true.
@@ -71,9 +82,20 @@ static struct usb_serial_driver debug_device = {
.process_read_urb = usb_debug_process_read_urb,
 };
 
+static struct usb_serial_driver dbc_device = {
+   .driver = {
+   .owner =THIS_MODULE,
+   .name = "xhci_dbc",
+   },
+   .id_table = dbc_id_table,
+   .num_ports =1,
+   .break_ctl =usb_debug_break_ctl,
+   .process_read_urb = usb_debug_process_read_urb,
+};
+
 static struct usb_serial_driver * const serial_drivers[] = {
-   _device, NULL
+   _device, _device, NULL
 };
 
-module_usb_serial_driver(serial_drivers, id_table);
+module_usb_serial_driver(serial_drivers, id_table_combined);
 MODULE_LICENSE("GPL");
-- 
2.1.4

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Re: [PATCH 01/12] usb: xhci: expose xhci extended capabilities via debugfs

[Lu, Baolu]

On 10/28/2015 08:40 PM, Greg Kroah-Hartman wrote:

+static const char *get_extcap_desc(u32 cap_id)
>+{
>+   switch (cap_id) {
>+   case XHCI_EXT_CAPS_LEGACY:
>+   return "USB Legacy Support";
>+   case XHCI_EXT_CAPS_PROTOCOL:
>+   return "Supported Protocol";
>+   case XHCI_EXT_CAPS_PM:
>+   return "Extended Power Management";
>+   case XHCI_EXT_CAPS_VIRT:
>+   return "I/O Virtualization (xHCI-IOV)";
>+   case XHCI_EXT_CAPS_ROUTE:
>+   return "Message Interrupt";
>+   case XHCI_EXT_CAPS_LOCALMEM:
>+   return "Local Memory";
>+   case XHCI_EXT_CAPS_DEBUG:
>+   return "USB Debug Capability";

This is a lot more stuff than just debug port, it should be in sysfs
as individual files, not one big one that you somehow have to parse in
order to determine this information.



Hi Greg,

It's hard to put each extended capability into a individual sysfs file.

The extended capabilities are optional. One extended capability
might be supported in one hardware, but not in another. Also,
there are many "vendor defined" capabilities (ID range 192-255).
The vendor defined capabilities are not defined in xhci spec and
they could be used by the hardware vendor for various purposes.

The purpose of this patch is to let user know what kind of extended
capabilities does a host controller supported. For example, on
one of my develop machines, it prints,

@addr(virt)CAP_IDDescription
@c90001c8800002Supported Protocol
@c90001c8802002Supported Protocol
@c90001c88070c0Vendor Defined
@c90001c8846c01USB Legacy Support
@c90001c884f4c6Vendor Defined
@c90001c88500c7Vendor Defined
@c90001c88600c2Vendor Defined
@c90001c887000aUSB Debug Capability
@c90001c88740c3Vendor Defined
@c90001c88800c4Vendor Defined
@c90001c88900c5Vendor Defined

With this output I know that "USB Debug Capability" is supported
in my machine.

Thanks,
Baolu
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Re: [PATCH 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu, Baolu]

On 10/28/2015 08:33 PM, Greg Kroah-Hartman wrote:

On Wed, Oct 28, 2015 at 04:00:42PM +0800, Lu Baolu wrote:

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  drivers/usb/serial/usb_debug.c | 29 ++---
  1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..d4903b0 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
  };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);

You shouldn't need a "combined" module device table anymore, the module
core was changed a while ago to remove that restriction, you should be
able to just multiple exports of MODULE_DEVICE_TABLE and everything
should "just work" on the export side.  Now it might not work on the usb
core side, but that's a different issue...


Before I dive into the serial driver code, can anybody tell me, if
I remove the "combined" module device table, what should I
specify the second parameter for module_usb_serial_driver()?

The previous declaration is,

module_usb_serial_driver(serial_drivers, id_table_combined);

Thanks,
Baolu



thanks,

greg k-h



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Re: [PATCH 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu, Baolu]

On 10/30/2015 10:41 PM, Greg Kroah-Hartman wrote:

On Fri, Oct 30, 2015 at 07:46:45PM +0800, Lu, Baolu wrote:


On 10/28/2015 08:33 PM, Greg Kroah-Hartman wrote:

On Wed, Oct 28, 2015 at 04:00:42PM +0800, Lu Baolu wrote:

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
  drivers/usb/serial/usb_debug.c | 29 ++---
  1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..d4903b0 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
  };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);

You shouldn't need a "combined" module device table anymore, the module
core was changed a while ago to remove that restriction, you should be
able to just multiple exports of MODULE_DEVICE_TABLE and everything
should "just work" on the export side.  Now it might not work on the usb
core side, but that's a different issue...

Before I dive into the serial driver code, can anybody tell me, if
I remove the "combined" module device table, what should I
specify the second parameter for module_usb_serial_driver()?

The previous declaration is,

module_usb_serial_driver(serial_drivers, id_table_combined);

Yeah, that's the issue I was alluding to here, maybe this will not work
just yet for USB serial drivers, sorry to lead you down the wrong path.
Your original patch should be fine for now.


Okay, I will keep that patch.



thanks,

greg k-h


Thanks,
Baolu


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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

Hi Steinar,

Do you mind trying attached patch? This is not a fix but to verify
whether LPM really works when only one device is used. You can
follow below steps:

1) apply the attached patch on top the latest kernel.
2) build and install the kernel.
3) boot your machine with the new kernel.
4) insert one  Blackmagic Design device into USB3 root port.
7) wait for a few seconds
6) check below sysfs nodes:

$ cat /sys/bus/usb/devices//power/usb3_hardware_lpm_u1
$ cat /sys/bus/usb/devices//power/usb3_hardware_lpm_u2

Can you please post values of above two sysfs nodes?
A copy of dmesg will also be helpful.

Thanks,
Baolu

On 11/05/2015 02:23 AM, Steinar H. Gunderson wrote:

On Mon, Nov 02, 2015 at 04:00:42PM -0500, Alan Stern wrote:

That commit was included in (approximately) the 4.1.5 or later stable
kernel, and it is included in 4.2.  You should be able to put one of
those on a bootable USB stick.

I tried going down this route. After some back and forth, I realize that...
the machine has only two USB ports, so I can't boot off USB stick and still
test how it behaves with two cards. (I could buy a hub, but that would surely
introduce new potential errors in the mix.)

So I'm afraid I can't help you at this point. My recommendation to include
the patch still stands, though.

/* Steinar */


>From c8cd71a0703cf26cfca9d89a3ad451f79c7232af Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu...@linux.intel.com>
Date: Thu, 5 Nov 2015 14:08:48 +0800
Subject: [PATCH 1/2] usb: core: LPM: fix usb3_hardware_lpm sysfs node

Commit 655fe4effe0f ("usbcore: add sysfs support to xHCI usb3
hardware LPM") introduced usb3_hardware_lpm sysfs node. This
doesn't show the correct status of USB3 U1 and U2 LPM status.

This patch fixes this by replacing usb3_hardware_lpm with two
nodes, usb3_hardware_lpm_u1 (for U1) and usb3_hardware_lpm_u2
(for U2), and recording the U1/U2 LPM status in right places.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-bus-usb | 16 +---
 Documentation/usb/power-management.txt  | 11 ++-
 drivers/usb/core/hub.c  | 29 +
 drivers/usb/core/sysfs.c| 28 
 include/linux/usb.h |  2 ++
 5 files changed, 62 insertions(+), 24 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 3a4abfc..136ba17 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -134,19 +134,21 @@ Description:
 		enabled for the device. Developer can write y/Y/1 or n/N/0 to
 		the file to enable/disable the feature.
 
-What:		/sys/bus/usb/devices/.../power/usb3_hardware_lpm
-Date:		June 2015
+What:		/sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
+		/sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
+Date:		November 2015
 Contact:	Kevin Strasser <kevin.stras...@linux.intel.com>
+		Lu Baolu <baolu...@linux.intel.com>
 Description:
 		If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
 		in to a xHCI host which supports link PM, it will check if U1
 		and U2 exit latencies have been set in the BOS descriptor; if
-		the check is is passed and the host supports USB3 hardware LPM,
+		the check is passed and the host supports USB3 hardware LPM,
 		USB3 hardware LPM will be enabled for the device and the USB
-		device directory will contain a file named
-		power/usb3_hardware_lpm. The file holds a string value (enable
-		or disable) indicating whether or not USB3 hardware LPM is
-		enabled for the device.
+		device directory will contain two files named
+		power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
+		files hold a string value (enable or disable) indicating whether
+		or not USB3 hardware LPM U1 or U2 is enabled for the device.
 
 What:		/sys/bus/usb/devices/.../removable
 Date:		February 2012
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt
index 4a15c90..0a94ffe 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -537,17 +537,18 @@ relevant attribute files are usb2_hardware_lpm and usb3_hardware_lpm.
 		can write y/Y/1 or n/N/0 to the file to	enable/disable
 		USB2 hardware LPM manually. This is for	test purpose mainly.
 
-	power/usb3_hardware_lpm
+	power/usb3_hardware_lpm_u1
+	power/usb3_hardware_lpm_u2
 
 		When a USB 3.0 lpm-capable device is plugged in to a
 		xHCI host which supports link PM, it will check if U1
 		and U2 exit latencies have been set in the BOS
 		descriptor; if the check is is passed and the host
 		supports USB3 hardware LPM, USB3 hardware LPM will be
-		enabled for the device and this file will be created.
-		The file holds a string value (enable or disable)
-		indicating whether or not USB3 hardware LPM is
-		enabled for the device.
+		enabled for the device and these files will be crea

Re: [PATCH 00/12] usb: early: add support for early printk through USB3 debug port

[Lu, Baolu]

On 11/03/2015 05:42 PM, Dave Young wrote:

On 10/28/15 at 04:00pm, Lu Baolu wrote:

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in debugfs, through which users can check
whether the debug capability is supported by a specific host controller.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.


Nice work, I want to try your patches. But I have only one machine with
debug capability, I think I can use it as debug target. Can I use another
machine with usb 3.0 but no debug capability as the debug host?


Yes, you can. The debug host doesn't require debug capability.

Please follow guide in patch 12 when you try it. It has been verified
on Intel Skylake machine.



BTW, I hacked a cable according to usb 3 spec, cut vbus/d+/d-, cross wired
ss pins.


Good luck. I just bought one from

http://www.datapro.net/products/usb-3-0-super-speed-a-a-debugging-cable.html.



Thanks
Dave



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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

On 11/06/2015 02:45 AM, Steinar H. Gunderson wrote:

On Thu, Nov 05, 2015 at 04:12:24PM +0800, Lu, Baolu wrote:

1) apply the attached patch on top the latest kernel.

I applied on top of a clean 4.3.0.


$ cat /sys/bus/usb/devices//power/usb3_hardware_lpm_u1
$ cat /sys/bus/usb/devices//power/usb3_hardware_lpm_u2

klump:~> cat /sys/bus/usb/devices/2-2/product
Intensity Shuttle
klump:~> cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u1
disabled
klump:~> cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u2
disabled


Thank you.

Have you set CONFIG_PM? Can you reproduce the problem with this kernel?




Can you please post values of above two sysfs nodes?
A copy of dmesg will also be helpful.

Attached.

/* Steinar */


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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

On 11/06/2015 08:45 AM, Steinar H. Gunderson wrote:

On Fri, Nov 06, 2015 at 08:39:28AM +0800, Lu, Baolu wrote:

Have you set CONFIG_PM?

Yes. CONFIG_PM=y.


Can you reproduce the problem with this kernel?

I reproduced the U1/U2 disconnect issues several times. I didn't try the
issue of not enough bandwidth for two devices.


Can you please try the not enough bandwidth issue?

Can you cat /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u1
and /sys/bus/usb/devices/2-2/power/usb3_hardware_lpm_u2 for several
times? Don't use that device when cat these two files.

I am hoping that LPM works when only one device is used (hence
there is enough bus bandwidth).



/* Steinar */


Thanks,
Baolu
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Re: Overly conservative xHCI bandwidth estimation

[Lu, Baolu]

I could spend some time on this issue a week later.
I'd like to check whether there is any bugs in the driver itself.
Otherwise, blacklist this specific device for LPM.

Thanks,
Baolu

On 10/21/2015 07:05 AM, Steinar H. Gunderson wrote:

On Mon, Sep 28, 2015 at 02:32:13PM +0200, Steinar H. Gunderson wrote:

Just so that it doesn't get lost: I've reported issues with this specific
device and LPM not too long ago. It's entirely possible that the device
somehow is broken, although it works in Windows 7/8/10 and OS X, from what I
know, and at least Windows 10 uses USB3 LPM.

Perhaps figuring out what's wrong with the ping timeouts would also fix this
issue? I'm afraid I don't have any fancy USB analyzer equipment to debug
with, though.

In any case, I'll reiterate my request to turn off LPM for a specific device,
no matter whose fault these specific issues are. :-)

Is there anything else I can do to help fixing these issues? (U1/U2 timeouts
causing disconnects, and xHCI bandwidth estimation being off.) I've been
running with CONFIG_PM=n for a while now, but it is obviously not a good
place to be for a laptop.

/* Steinar */


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[PATCH v4 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk

[Lu Baolu]

On Intel platforms, if the debug target is connected with debug
host, enabling DCE bit in command register leads to a port hung
state. In the hung state, the host system will not see a port
connected status bit set. Hence debug target fails to be probed.

The state could be resolved by performing a port reset to the
debug port from the host xHCI. This patch introduces this work
around.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 52 
 include/linux/usb/xhci-dbc.h |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 22a1de9..6b23f09 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -255,6 +255,8 @@ static void __iomem *xdbc_map_pci_mmio(u32 bus,
xdbcp->bar = bar;
xdbcp->xhci_base = base;
xdbcp->xhci_length = sz64;
+   xdbcp->vendor = read_pci_config_16(bus, dev, func, PCI_VENDOR_ID);
+   xdbcp->device = read_pci_config_16(bus, dev, func, PCI_DEVICE_ID);
 
if (length)
*length = sz64;
@@ -651,6 +653,52 @@ static int xdbc_mem_init(void)
return 0;
 }
 
+static void xdbc_reset_debug_port_callback(int cap_offset, void *data)
+{
+   u8 major;
+   u32 val, port_offset, port_count;
+   u32 cap_length;
+   void __iomem *ops_reg;
+   void __iomem *portsc;
+   int i;
+
+   val = readl(xdbcp->xhci_base + cap_offset);
+   major = (u8) XHCI_EXT_PORT_MAJOR(val);
+
+   /* only reset super-speed port */
+   if (major != 0x3)
+   return;
+
+   val = readl(xdbcp->xhci_base + cap_offset + 8);
+   port_offset = XHCI_EXT_PORT_OFF(val);
+   port_count = XHCI_EXT_PORT_COUNT(val);
+   xdbc_trace("Extcap Port offset %d count %d\n",
+   port_offset, port_count);
+
+   cap_length = readl(xdbcp->xhci_base) & 0xff;
+   ops_reg = xdbcp->xhci_base + cap_length;
+
+   port_offset--;
+   for (i = port_offset; i < (port_offset + port_count); i++) {
+   portsc = ops_reg + 0x400 + i * 0x10;
+   val = readl(portsc);
+   /* reset the port if CCS bit is cleared */
+   if (!(val & 0x1))
+   writel(val | (1 << 4), portsc);
+   }
+}
+
+static void xdbc_reset_debug_port(void)
+{
+   xdbc_walk_excap(xdbcp->bus,
+   xdbcp->dev,
+   xdbcp->func,
+   XHCI_EXT_CAPS_PROTOCOL,
+   false,
+   xdbc_reset_debug_port_callback,
+   NULL);
+}
+
 /*
  * xdbc_start: start DbC
  *
@@ -669,6 +717,10 @@ static int xdbc_start(void)
return -ENODEV;
}
 
+   /* reset port to avoid bus hang */
+   if (xdbcp->vendor == PCI_VENDOR_ID_INTEL)
+   xdbc_reset_debug_port();
+
/* wait for port connection */
if (handshake(>xdbc_reg->portsc, PORTSC_CCS,
PORTSC_CCS, 500, 100) < 0) {
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 153fb87..fc0ef9a 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -128,6 +128,8 @@ struct xdbc_state {
u32 dev;
u32 func;
u8  bar;
+   u16 vendor;
+   u16 device;
void __iomem*xhci_base;
size_t  xhci_length;
 #defineXDBC_PCI_MAX_BUSES  256
-- 
2.1.4

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[PATCH v4 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

Hi,

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in sysfs, through which users can check
whether the debug capability is supported by a specific host controller,
and the hardware state.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.

Change log:
v1->v2:
(1) Patch 1 re-implemented. "debugfs" has been replaced with sysfs.
The scope reduced from all extended capabilities to debug port
specific.
(2) Patch 11 changed. Removed unnecessary .bulk_out_size setting.

v2->v3:
(1) Patch 11 got acked by Johan Hovold.

v3->v4:
(1) Patch 1 code refactored by using xhci_find_ext_cap_by_id() helper.
(2) Patch 3 "bus hung state" changed to "port hung state" in commit message.
(3) Patch 12 added verified platform information.

Lu Baolu (12):
  usb: xhci: add sysfs file for xHCI debug port
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: xhci: dbc: probe and setup xhci debug capability
  usb: xhci: dbc: add support for Intel xHCI dbc quirk
  usb: xhci: dbc: add debug buffer
  usb: xhci: dbc: add bulk out and bulk in interfaces
  usb: xhci: dbc: handle dbc-configured exit
  usb: xhci: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: xhci: dbc: add handshake between debug target and host
  usb: serial: usb_debug: add support for dbc debug device
  usb: doc: add document for xHCI DbC driver

 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |   23 +
 Documentation/kernel-parameters.txt|1 +
 Documentation/usb/xhci-dbc.txt |  325 +
 MAINTAINERS|8 +
 arch/x86/Kconfig.debug |   12 +
 arch/x86/include/asm/fixmap.h  |4 +
 arch/x86/kernel/early_printk.c |5 +
 drivers/usb/early/Makefile |1 +
 drivers/usb/early/xhci-dbc.c   | 1407 
 drivers/usb/host/Makefile  |2 +-
 drivers/usb/host/xhci-ext-caps.h   |   14 +-
 drivers/usb/host/xhci-sysfs.c  |   80 ++
 drivers/usb/host/xhci.c|4 +
 drivers/usb/host/xhci.h|4 +
 drivers/usb/serial/usb_debug.c |   28 +-
 include/linux/usb/xhci-dbc.h   |  224 
 16 files changed, 2137 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 drivers/usb/host/xhci-sysfs.c
 create mode 100644 include/linux/usb/xhci-dbc.h

Thanks,
-Baolu
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2.1.4

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[PATCH v4 07/12] usb: xhci: dbc: handle dbc-configured exit

[Lu Baolu]

DbC might exit configured state in some cases (refer to 7.6.4.4 in
xHCI spec 1.1). Software needs detect and clear this situation by
clearing DCCTRL.DCR and wait until the DbC configured before read
or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 28 
 1 file changed, 28 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index f51daa4..8a5a51f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1153,6 +1153,29 @@ static int xdbc_wait_until_bulk_done(struct xdbc_trb 
*trb, int loops)
return -EIO;
 }
 
+static int xdbc_wait_until_dbc_configured(void)
+{
+   int timeout = 0;
+   u32 reg;
+
+   /* Port exits configured state */
+   reg = readl(>xdbc_reg->control);
+   if (!(reg & CTRL_DRC))
+   return 0;
+
+   /* clear run change bit (RW1C) */
+   writel(reg | CTRL_DRC, >xdbc_reg->control);
+
+   do {
+   if (readl(>xdbc_reg->control) & CTRL_DCR)
+   return 0;
+
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1167,6 +1190,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EINVAL;
}
 
+   if (xdbc_wait_until_dbc_configured()) {
+   xdbc_trace("%s: hardware not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v4 08/12] usb: xhci: dbc: handle endpoint stall

[Lu Baolu]

In case of endpoint stall, software is able to detect the situation
by reading DCCTRL.HIT or DCCTRL.HOT bits. DbC follows the normal USB
framework to handle endpoint stall. When software detects endpoint
stall situation, it should wait until endpoint is recovered before
read or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 36 
 1 file changed, 36 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 8a5a51f..aaf655f 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1176,6 +1176,37 @@ static int xdbc_wait_until_dbc_configured(void)
return -ETIMEDOUT;
 }
 
+static int xdbc_wait_until_epstall_cleared(bool read)
+{
+   int timeout = 0;
+
+   if (read) {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HIT)) {
+   xdbcp->in_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->in_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   } else {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HOT)) {
+   xdbcp->out_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->out_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   }
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1195,6 +1226,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EPERM;
}
 
+   if (xdbc_wait_until_epstall_cleared(read)) {
+   xdbc_trace("%s: endpoint not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v4 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu Baolu]

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Acked-by: Johan Hovold <jo...@kernel.org>
---
 drivers/usb/serial/usb_debug.c | 28 +---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..92f7e5c 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
 };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);
 
 /* This HW really does not support a serial break, so one will be
  * emulated when ever the break state is set to true.
@@ -71,9 +82,20 @@ static struct usb_serial_driver debug_device = {
.process_read_urb = usb_debug_process_read_urb,
 };
 
+static struct usb_serial_driver dbc_device = {
+   .driver = {
+   .owner =THIS_MODULE,
+   .name = "xhci_dbc",
+   },
+   .id_table = dbc_id_table,
+   .num_ports =1,
+   .break_ctl =usb_debug_break_ctl,
+   .process_read_urb = usb_debug_process_read_urb,
+};
+
 static struct usb_serial_driver * const serial_drivers[] = {
-   _device, NULL
+   _device, _device, NULL
 };
 
-module_usb_serial_driver(serial_drivers, id_table);
+module_usb_serial_driver(serial_drivers, id_table_combined);
 MODULE_LICENSE("GPL");
-- 
2.1.4

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[PATCH v4 12/12] usb: doc: add document for xHCI DbC driver

[Lu Baolu]

Add Documentation/usb/xhci-dbc.txt. This document includes
development status and user guide for USB3 debug port.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/usb/xhci-dbc.txt | 325 +
 MAINTAINERS|   1 +
 drivers/usb/early/xhci-dbc.c   |   3 +
 3 files changed, 329 insertions(+)
 create mode 100644 Documentation/usb/xhci-dbc.txt

diff --git a/Documentation/usb/xhci-dbc.txt b/Documentation/usb/xhci-dbc.txt
new file mode 100644
index 000..441b40c
--- /dev/null
+++ b/Documentation/usb/xhci-dbc.txt
@@ -0,0 +1,325 @@
+xHCI debug capability driver
+
+         Lu Baolu <baolu...@linux.intel.com>
+
+Last-updated: September 2015
+
+
+   Contents:
+   -
+   * What is xHCI DbC?
+   * Debug topologies
+   * Debug stacks
+   * Port Multiplexing
+   * Hardware initialization
+   * External reset
+   * Port reset
+   * Interrupt/DMA/Memory during early boot
+   * Endpoint STALL
+   * Debug device information
+   * How to use DbC early printk?
+   * Limitations
+
+   What is xHCI DbC?
+   -
+
+The xHCI Debugging Capability defined in section 7.6 of xHCI spec 1.1
+provides an optional functionality that enables low-level system debug
+over USB. It provides a means of connecting two systems where one system
+is a Debug Host and the other a Debug Target (System Under Test). The
+Debug Capability provides an interface that is completely independent
+of the xHCI interface. A Debug Target enumerates as a USB debug device
+to the Debug Host, allowing a Debug Host to access a Debug Target through
+the standard USB software stack.
+
+   Debug topologies
+   
+
+Multiple Debug Targets may be attached to a single Debug Host. Debug
+Targets may be connected to any downstream facing port below a Debug
+Host (i.e. anywhere in the fabric, root port or external hub puts).
+A Debug Target may only connect to a Debug Host through a Root Hub port
+of the target. That means connection of a Debug Target to a Debug Host
+through the ports of an external hub is not supported.
+
+Below is a typical connection between Debug Host and Debug target. Two
+Debug targets are connected to a single Debug host.
+
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+  || |
+  ||_|
+  |_
+|
+ ___|
+|   HUB  |  |  Debug Target  |
+||  ||
+| Superspeed hub |  |  xHC with DbC  |
+||  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+   Debug stacks
+   
+
+Below is a software stack diagram of both Debug Host and Debug Target.
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|   debug App|  ||
+||  | system debug   |
+|   usb_debug|  | hooks  |
+||  ||
+|usbcore |  ||
+||  |debug capability|
+|xhci_hcd|  | driver |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+
+   Port Multiplexing
+   -
+
+A debug port is always multiplexed with the first xHCI root hub port.
+Whenever debug capability is supported and enabled, and the first root
+hub port is detected to be connected to a downstream super-speed port
+of a Debug Host, the r

[PATCH v4 05/12] usb: xhci: dbc: add debug buffer

[Lu Baolu]

"printk" is not suitable for dbc debugging especially when console
is in usage. This patch adds a debug buffer in dbc driver and puts
the debug messages in this local buffer. The debug buffer could be
dumped whenever the console is not in use. This part of code will
not be visible unless DBC_DEBUG is defined.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 62 ++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 6b23f09..b36a527 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,8 +32,64 @@ static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
 #ifdef DBC_DEBUG
-/* place holder */
-#definexdbc_trace  printk
+#defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
+#defineMSG_MAX_LINE128
+static char xdbc_debug_buf[XDBC_DEBUG_BUF_SIZE];
+static void xdbc_trace(const char *fmt, ...)
+{
+   int i, size;
+   va_list args;
+   static int pos;
+   char temp_buf[MSG_MAX_LINE];
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   return;
+
+   memset(temp_buf, 0, MSG_MAX_LINE);
+   va_start(args, fmt);
+   vsnprintf(temp_buf, MSG_MAX_LINE - 1, fmt, args);
+   va_end(args);
+
+   i = 0;
+   size = strlen(temp_buf);
+   while (i < size) {
+   xdbc_debug_buf[pos] = temp_buf[i];
+   pos++;
+   i++;
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   break;
+   }
+}
+
+static void xdbc_dump_debug_buffer(void)
+{
+   int index = 0;
+   int count = 0;
+   char dump_buf[MSG_MAX_LINE];
+
+   xdbc_trace("The end of DbC trace buffer\n");
+   pr_notice("DBC debug buffer:\n");
+   memset(dump_buf, 0, MSG_MAX_LINE);
+
+   while (index < XDBC_DEBUG_BUF_SIZE) {
+   if (!xdbc_debug_buf[index])
+   break;
+
+   if (xdbc_debug_buf[index] == '\n' ||
+   count >= MSG_MAX_LINE - 1) {
+   pr_notice("DBC: @%08x %s\n", index, dump_buf);
+   memset(dump_buf, 0, MSG_MAX_LINE);
+   count = 0;
+   } else {
+   dump_buf[count] = xdbc_debug_buf[index];
+   count++;
+   }
+
+   index++;
+   }
+}
+
 static void xdbc_dbg_dump_regs(char *str)
 {
if (!xdbcp->xdbc_reg) {
@@ -165,6 +221,7 @@ static void xdbc_dbg_dump_data(char *str)
 
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
+static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
 #endif /* DBC_DEBUG */
@@ -832,6 +889,7 @@ int __init early_xdbc_init(char *s)
pr_notice("failed to setup xHCI DbC connection\n");
xdbcp->xhci_base = NULL;
xdbcp->xdbc_reg = NULL;
+   xdbc_dump_debug_buffer();
return ret;
}
 
-- 
2.1.4

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[PATCH v4 10/12] usb: xhci: dbc: add handshake between debug target and host

[Lu Baolu]

After DbC setup, debug target needs to wait until tty driver and
application (e.g. mincom) on debug taget start.  Otherwise, out
messages might be ignored.

This patch adds a ping/pong mechanism between debug target and
host. Debug target will be waiting there until user presses 'Y'
or 'y' in the tty application.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 27 +++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 68a7139..b75c523 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,6 +32,9 @@
 static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
+static int early_xdbc_read(struct console *con, char *str, unsigned n);
+static void early_xdbc_write(struct console *con, const char *str, u32 n);
+
 #ifdef DBC_DEBUG
 #defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
 #defineMSG_MAX_LINE128
@@ -873,8 +876,12 @@ int __init early_xdbc_init(char *s)
 {
u32 bus = 0, dev = 0, func = 0;
unsigned long dbgp_num = 0;
+   char *ping = "Press Y to continue...\n";
+   char pong[64];
+   size_t size;
u32 offset;
int ret;
+   int retry = 20;
 
if (!early_pci_allowed())
return -EPERM;
@@ -917,6 +924,21 @@ int __init early_xdbc_init(char *s)
return ret;
}
 
+   while (retry > 0) {
+   early_xdbc_write(NULL, ping, strlen(ping));
+   size = early_xdbc_read(NULL, pong, 64);
+   if (size > 0) {
+   xdbc_trace("%s: pong message: %s\n", __func__, pong);
+   if (pong[0] == 'Y' || pong[0] == 'y')
+   break;
+   } else {
+   xdbc_trace("%s: pong message error %d\n",
+   __func__, size);
+   }
+
+   retry--;
+   }
+
return 0;
 }
 
@@ -1338,6 +1360,11 @@ int xdbc_bulk_write(const char *bytes, int size)
  * Start a bulk-in or bulk-out transfer, wait until transfer completion
  * or error. Return the count of actually transferred bytes or error.
  */
+static int early_xdbc_read(struct console *con, char *str, unsigned n)
+{
+   return xdbc_bulk_read(str, n, 0);
+}
+
 static void early_xdbc_write(struct console *con, const char *str, u32 n)
 {
int chunk, ret;
-- 
2.1.4

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[PATCH v4 09/12] x86: early_printk: add USB3 debug port earlyprintk support

[Lu Baolu]

Add support for early printk by writing debug messages to the USB3
debug port. Users can use this type of early printk by specifying
kernel parameter of "earlyprintk=xdbc". This gives users a chance
of providing debug output.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/kernel-parameters.txt |  1 +
 arch/x86/kernel/early_printk.c  |  5 +
 drivers/usb/early/xhci-dbc.c| 43 +
 include/linux/usb/xhci-dbc.h|  5 +
 4 files changed, 54 insertions(+)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index f8aae63..cb879cd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1049,6 +1049,7 @@ bytes respectively. Such letter suffixes can also be 
entirely omitted.
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
earlyprintk=pciserial,bus:device.function[,baudrate]
+   earlyprintk=xdbc[xhciController#]
 
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 21bf924..ba4c471 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -373,6 +374,10 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
early_console_register(_dbgp_console, keep);
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   if (!strncmp(buf, "xdbc", 4) && !early_xdbc_init(buf + 4))
+   early_console_register(_xdbc_console, keep);
+#endif
 #ifdef CONFIG_HVC_XEN
if (!strncmp(buf, "xen", 3))
early_console_register(_console, keep);
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index aaf655f..68a7139 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -10,6 +10,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include 
 #include 
 #include 
 #include 
@@ -1332,3 +1333,45 @@ int xdbc_bulk_write(const char *bytes, int size)
 
return ret;
 }
+
+/*
+ * Start a bulk-in or bulk-out transfer, wait until transfer completion
+ * or error. Return the count of actually transferred bytes or error.
+ */
+static void early_xdbc_write(struct console *con, const char *str, u32 n)
+{
+   int chunk, ret;
+   static char buf[XDBC_MAX_PACKET];
+   int use_cr = 0;
+
+   if (!xdbcp->xdbc_reg)
+   return;
+   memset(buf, 0, XDBC_MAX_PACKET);
+   while (n > 0) {
+   for (chunk = 0; chunk < XDBC_MAX_PACKET && n > 0;
+str++, chunk++, n--) {
+   if (!use_cr && *str == '\n') {
+   use_cr = 1;
+   buf[chunk] = '\r';
+   str--;
+   n++;
+   continue;
+   }
+   if (use_cr)
+   use_cr = 0;
+   buf[chunk] = *str;
+   }
+   if (chunk > 0) {
+   ret = xdbc_bulk_write(buf, chunk);
+   if (ret < 0)
+   break;
+   }
+   }
+}
+
+struct console early_xdbc_console = {
+   .name = "earlyxdbc",
+   .write =early_xdbc_write,
+   .flags =CON_PRINTBUFFER,
+   .index =-1,
+};
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 289ba58..a556eb8 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -216,4 +216,9 @@ struct xdbc_state {
 #definexdbc_read64(regs)   xhci_read_64(NULL, (regs))
 #definexdbc_write64(val, regs) xhci_write_64(NULL, (val), (regs))
 
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+extern int early_xdbc_init(char *s);
+extern struct console early_xdbc_console;
+#endif /* CONFIG_EARLY_PRINTK_XDBC */
+
 #endif /* __LINUX_XHCI_DBC_H */
-- 
2.1.4

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[PATCH v4 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu Baolu]

This patch adds a sysfs file for users to check 1) whether the debug
capability is implemented by hardware; 2) if supported, which state
does it stay at.

With a host that supports debug port, a file named "debug_port_state"
will be created under the device sysfs directory. Reading this file
will show users the state (disabled, enabled or configured) of the
debug port.

With a host that does NOT support debug port, "debug_port_state" file
won't be created.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd | 23 +++
 drivers/usb/host/Makefile  |  2 +-
 drivers/usb/host/xhci-ext-caps.h   | 14 +++-
 drivers/usb/host/xhci-sysfs.c  | 80 ++
 drivers/usb/host/xhci.c|  4 ++
 drivers/usb/host/xhci.h|  4 ++
 6 files changed, 125 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 drivers/usb/host/xhci-sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd 
b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
new file mode 100644
index 000..dd3e722
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -0,0 +1,23 @@
+What:  /sys/bus/pci/drivers/xhci_hcd/.../debug_port_state
+Date:  November 2015
+KernelVersion: 4.3.0
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   This file is designed for users to check the state of a
+   USB3 debug port. On a machine which supports USB3 debug
+   port, this file will be created. Reading this file will
+   show the state (disabled, enabled or configured) of the
+   debug port. On a machine that doesn't support USB3 debug
+   port, this file doesn't exist.
+
+   The state of a debug port could be:
+   1) disabled: The debug port is not enabled and the root
+   port has been switched to xHCI host as a normal
+   root port.
+   2) enabled: The debug port is enabled. The debug port
+   has been assigned to debug capability. The debug
+   capability is able to handle the control requests
+   defined in USB3 spec.
+   3) configured: The debug port has been enumerated by the
+   debug host as a debug device. The debug port is
+   in use now.
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index e7558ab..810c304 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -12,7 +12,7 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
-xhci-hcd-y += xhci-trace.o
+xhci-hcd-y += xhci-trace.o xhci-sysfs.o
 
 xhci-plat-hcd-y := xhci-plat.o
 ifneq ($(CONFIG_USB_XHCI_MVEBU), )
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 9fe3225..12c87e5 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -49,8 +49,15 @@
 #define XHCI_EXT_CAPS_PM   3
 #define XHCI_EXT_CAPS_VIRT 4
 #define XHCI_EXT_CAPS_ROUTE5
-/* IDs 6-9 reserved */
+#define XHCI_EXT_CAPS_LOCALMEM 6
+/* IDs 7-9 reserved */
 #define XHCI_EXT_CAPS_DEBUG10
+/* IDs 192-255 vendor specific */
+#define XHCI_EXT_CAPS_VEN_START192
+#define XHCI_EXT_CAPS_VEN_END  255
+#define XHCI_EXT_CAPS_VENDOR(p)(((p) >= XHCI_EXT_CAPS_VEN_START) && \
+   ((p) <= XHCI_EXT_CAPS_VEN_END))
+#define XHCI_EXT_MAX_CAPID XHCI_EXT_CAPS_VEN_END
 /* USB Legacy Support Capability - section 7.1.1 */
 #define XHCI_HC_BIOS_OWNED (1 << 16)
 #define XHCI_HC_OS_OWNED   (1 << 24)
@@ -73,6 +80,11 @@
 #define XHCI_HLC   (1 << 19)
 #define XHCI_BLC   (1 << 20)
 
+/* Debug capability - section 7.6.8 */
+#define XHCI_DBC_DCCTRL0x20
+#define XHCI_DBC_DCCTRL_DCR(1 << 0)
+#defineXHCI_DBC_DCCTRL_DCE (1 << 31)
+
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/
 #define XHCI_CMD_RUN   (1 << 0)
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 000..365858f
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,80 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free 

[PATCH v4 03/12] usb: xhci: dbc: probe and setup xhci debug capability

[Lu Baolu]

xHCI debug capability (DbC) is an optional functionality provided
by an xHCI host controller. Software learns this capability by
walking through the extended capability list in mmio of the host.

This patch introduces the code to probe and initialize the debug
capability hardware during early boot. With hardware initialization
done, the debug target (system under debug which has DbC enabled)
will present a debug device through the debug port. The debug device
is fully compliant with the USB framework and provides the equivalent
of a very high performance (USB3) full-duplex serial link between the
debug host and target.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 MAINTAINERS  |   7 +
 arch/x86/Kconfig.debug   |  12 +
 drivers/usb/early/Makefile   |   1 +
 drivers/usb/early/xhci-dbc.c | 787 +++
 include/linux/usb/xhci-dbc.h | 187 ++
 5 files changed, 994 insertions(+)
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

diff --git a/MAINTAINERS b/MAINTAINERS
index e9caa4b..3d7e0cf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11250,6 +11250,13 @@ S: Supported
 F: drivers/usb/host/xhci*
 F: drivers/usb/host/pci-quirks*
 
+USB XHCI DEBUG PORT
+M:     Lu Baolu <baolu...@linux.intel.com>
+L: linux-usb@vger.kernel.org
+S: Supported
+F: drivers/usb/early/xhci-dbc.c
+F: include/linux/usb/xhci-dbc.h
+
 USB ZD1201 DRIVER
 L: linux-wirel...@vger.kernel.org
 W: http://linux-lc100020.sourceforge.net
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 137dfa9..e450f88 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -65,6 +65,18 @@ config EARLY_PRINTK_EFI
  This is useful for kernel debugging when your machine crashes very
  early before the console code is initialized.
 
+config EARLY_PRINTK_XDBC
+   bool "Early printk via xHCI debug port"
+   depends on EARLY_PRINTK && PCI
+   ---help---
+ Write kernel log output directly into the xHCI debug port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash.
+
 config X86_PTDUMP_CORE
def_bool n
 
diff --git a/drivers/usb/early/Makefile b/drivers/usb/early/Makefile
index 24bbe51..2db5906 100644
--- a/drivers/usb/early/Makefile
+++ b/drivers/usb/early/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_EARLY_PRINTK_DBGP) += ehci-dbgp.o
+obj-$(CONFIG_EARLY_PRINTK_XDBC) += xhci-dbc.o
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
new file mode 100644
index 000..22a1de9
--- /dev/null
+++ b/drivers/usb/early/xhci-dbc.c
@@ -0,0 +1,787 @@
+/**
+ * xhci-dbc.c - xHCI debug capability driver
+ *
+ * Copyright (C) 2015 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ * Some code shared with EHCI debug port and xHCI driver.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include "../host/xhci.h"
+
+#defineXDBC_PROTOCOL   1   /* GNU Remote Debug Command Set 
*/
+#defineXDBC_VENDOR_ID  0x1d6b  /* Linux Foundation 0x1d6b */
+#defineXDBC_PRODUCT_ID 0x0004  /* __le16 idProduct; device 
0004 */
+#defineXDBC_DEVICE_REV 0x0010  /* 0.10 */
+
+static struct xdbc_state xdbc_stat;
+static struct xdbc_state *xdbcp = _stat;
+
+#ifdef DBC_DEBUG
+/* place holder */
+#definexdbc_trace  printk
+static void xdbc_dbg_dump_regs(char *str)
+{
+   if (!xdbcp->xdbc_reg) {
+   xdbc_trace("register not mapped\n");
+   return;
+   }
+
+   xdbc_trace("XDBC registers: %s\n", str);
+   xdbc_trace("  Capability: %08x\n",
+   readl(>xdbc_reg->capability));
+   xdbc_trace("  Door bell: %08x\n",
+   readl(>xdbc_reg->doorbell));
+   xdbc_trace("  Event Ring Segment Table Size: %08x\n",
+   readl(>xdbc_reg->ersts));
+   xdbc_trace("  Event Ring Segment Table Base Address: %16llx\n",
+   xdbc_read64(>xdbc_reg->erstba));
+   xdbc_trace("  Event Ring Dequeue Pointer: %16llx\n",
+   xdbc_read64(>xdbc_reg->erdp));
+   xdbc_trace("  Port status and control: %08x\n",
+   readl(&g

[PATCH v4 02/12] x86: fixmap: add permanent fixmap for xhci debug port

[Lu Baolu]

xHCI compatible USB3 host controller may provide debug capability
which enables low-level system debug over USB. In order to probing
this debug capability, Linux kernel needs to map and access the
mmio of the host controller during early boot.

This patch adds permenent fixmap pages in fixed_addresses table for
xHCI mmio access.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 arch/x86/include/asm/fixmap.h | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index f80d700..fbf452f 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -82,6 +82,10 @@ enum fixed_addresses {
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
FIX_OHCI1394_BASE,
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   FIX_XDBC_BASE,
+   FIX_XDBC_END = FIX_XDBC_BASE + 15,
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
 #endif
-- 
2.1.4

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[PATCH v4 06/12] usb: xhci: dbc: add bulk out and bulk in interfaces

[Lu Baolu]

This patch adds interfaces for bulk out and bulk in ops. These
interfaces could be used to implement early printk bootconsole
or hook to various system debuggers.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 373 +++
 include/linux/usb/xhci-dbc.h |  30 
 2 files changed, 403 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index b36a527..f51daa4 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -219,11 +219,21 @@ static void xdbc_dbg_dump_data(char *str)
xdbc_dbg_dump_string("String Descriptor:");
 }
 
+static void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str)
+{
+   xdbc_trace("DBC trb: %s\n", str);
+   xdbc_trace("@%016llx %08x %08x %08x %08x\n", (u64)__pa(trb),
+   le32_to_cpu(trb->field[0]),
+   le32_to_cpu(trb->field[1]),
+   le32_to_cpu(trb->field[2]),
+   le32_to_cpu(trb->field[3]));
+}
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
 static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
+static inline void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str) { }
 #endif /* DBC_DEBUG */
 
 /*
@@ -334,6 +344,7 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
static char in_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char out_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char table_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+   static char bulk_buf_page[PAGE_SIZE] __aligned(PAGE_SIZE);
 
switch (type) {
case XDBC_PAGE_EVENT:
@@ -348,6 +359,9 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
case XDBC_PAGE_TABLE:
virt = (void *)table_page;
break;
+   case XDBC_PAGE_BUFFER:
+   virt = (void *)bulk_buf_page;
+   break;
default:
return NULL;
}
@@ -707,6 +721,12 @@ static int xdbc_mem_init(void)
dev_info = cpu_to_le32((XDBC_DEVICE_REV << 16) | XDBC_PRODUCT_ID);
writel(dev_info, >xdbc_reg->devinfo2);
 
+   /* get and store the transfer buffer */
+   xdbcp->out_buf = xdbc_get_page(>out_dma,
+   XDBC_PAGE_BUFFER);
+   xdbcp->in_buf = xdbcp->out_buf + XDBC_MAX_PACKET;
+   xdbcp->in_dma = xdbcp->out_dma + XDBC_MAX_PACKET;
+
return 0;
 }
 
@@ -802,6 +822,9 @@ static int xdbc_start(void)
 
xdbc_trace("root hub port number %d\n", DCST_DPN(status));
 
+   xdbcp->in_ep_state = EP_RUNNING;
+   xdbcp->out_ep_state = EP_RUNNING;
+
xdbc_trace("DbC is running now, control 0x%08x\n",
readl(>xdbc_reg->control));
 
@@ -895,3 +918,353 @@ int __init early_xdbc_init(char *s)
 
return 0;
 }
+
+static void xdbc_queue_trb(struct xdbc_ring *ring,
+   u32 field1, u32 field2, u32 field3, u32 field4)
+{
+   struct xdbc_trb *trb, *link_trb;
+
+   trb = ring->enqueue;
+   trb->field[0] = cpu_to_le32(field1);
+   trb->field[1] = cpu_to_le32(field2);
+   trb->field[2] = cpu_to_le32(field3);
+   trb->field[3] = cpu_to_le32(field4);
+
+   xdbc_dbg_dump_trb(trb, "enqueue trb");
+
+   ++(ring->enqueue);
+   if (ring->enqueue >= >segment->trbs[TRBS_PER_SEGMENT - 1]) {
+   link_trb = ring->enqueue;
+   if (ring->cycle_state)
+   link_trb->field[3] |= cpu_to_le32(TRB_CYCLE);
+   else
+   link_trb->field[3] &= cpu_to_le32(~TRB_CYCLE);
+
+   ring->enqueue = ring->segment->trbs;
+   ring->cycle_state ^= 1;
+   }
+}
+
+static void xdbc_ring_doorbell(int target)
+{
+   writel(DOOR_BELL_TARGET(target), >xdbc_reg->doorbell);
+}
+
+static void xdbc_handle_port_status(struct xdbc_trb *evt_trb)
+{
+   u32 port_reg;
+
+   port_reg = readl(>xdbc_reg->portsc);
+
+   if (port_reg & PORTSC_CSC) {
+   xdbc_trace("%s: connect status change event\n", __func__);
+   writel(port_reg | PORTSC_CSC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PRC) {
+   xdbc_trace("%s: port reset change event\n", __func__);
+   writel(port_reg | PORTSC_PRC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PLC) {
+   xdbc_trace("%s: port link status change event\n", __func__);
+   writel(

Re: [PATCH] USB: EHCI: fix dereference of ERR_PTR

[Lu, Baolu]

On 09/16/2015 10:08 PM, Sudip Mukherjee wrote:

On error find_tt() returns either a NULL pointer or the error value in
ERR_PTR. But we were dereferencing it directly without even checking if
find_tt() returned a valid pointer or not.

Signed-off-by: Sudip Mukherjee 
---
  drivers/usb/host/ehci-sched.c | 4 
  1 file changed, 4 insertions(+)

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index f9a3327..27bced7 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -257,6 +257,8 @@ static void reserve_release_intr_bandwidth(struct ehci_hcd 
*ehci,
/* FS/LS bus bandwidth */
if (tt_usecs) {
tt = find_tt(qh->ps.udev);
+   if (!tt || IS_ERR(tt))


Why not IS_ERR_OR_NULL()?


+   return;
if (sign > 0)
list_add_tail(>ps.ps_list, >ps_list);
else
@@ -1373,6 +1375,8 @@ static void reserve_release_iso_bandwidth(struct ehci_hcd 
*ehci,
}
  
  		tt = find_tt(stream->ps.udev);

+   if (!tt || IS_ERR(tt))
+   return;
if (sign > 0)
list_add_tail(>ps.ps_list, >ps_list);
else


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Re: (4.3.0) r8152: deadlock related to runtime suspend?

[Lu Baolu]

Hi Peter,

Have you ever tried disabling auto-pm? Did things go smoothly if auto-pm is 
disabled?

I always disable usb auto-pm in below way.

# echo on | tee /sys/bus/usb/devices/*/power/control
# echo on > /sys/bus/pci/devices//power/control

Thanks,
Baolu

On 12/05/2015 06:59 PM, Peter Wu wrote:
> Hi,
>
> I rarely use a Realtek USB 3.0 Gigabit Ethernet adapter (vid/pid
> 0bda:8153), but when I did last night, it resulted in a lockup of
> processes doing networking ("ip link", "ping", "ethtool", ...).
>
> A (few) minute(s) before that event, I noticed that there was no network
> connectivity (ping hung) which was somehow solved by invoking "ethtool
> eth1" (triggering runtime pm wakeup?). This same trick did not work at
> the next event. Invoking "ethtool eth1", "ip link", etc. hung completely
> and interrupt (^C) did not work at all.
>
> Since that did not work, I pulled the USB adapter and re-inserted it,
> hoping it would reset things. That did not work at all, there was a
> "usb disconnect" message, but no further driver messages.
>
> Fast forward an hour, and it has become a disaster. I have terminated
> and killed many programs via SysRq but am still unable to get a stable
> system that does not hang on network I/O. Even the suspend process
> fails so in the end I attempted to shutdown the system. After half an
> hour after getting the poweroff message, I issued SysRq + B to reboot
> (since SysRq + O did not shut down either).
>
> Attached are logs with various various backtraces from SysRq and failed
> suspend. Let me know if you need more information!
>
> By the way, often I have to rmmod xhci and re-insert it, otherwise
> plugging it in does not result in a detection. A USB 2.0 port does not
> have this problem (runtime PM is enabled for all devices). This is the
> USB 3.0 port:
>
> 02:00.0 USB controller [0c03]: NEC Corporation uPD720200 USB 3.0
> Host Controller [1033:0194] (rev 03)

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Re: [PATCH] usb: host: iounmap before return

[Lu Baolu]

On 12/06/2015 09:47 PM, Geyslan G. Bem wrote:
> This patch fixes a 'quirk_usb_handoff_xhci()' branch return that was not 
> unmapping correctly.
>
> Coccinelle: scripts/coccinelle/free/iounmap.cocci
>
> Signed-off-by: Geyslan G. Bem 
> ---
>  drivers/usb/host/pci-quirks.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index f940056..64150dd 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -990,7 +990,7 @@ static void quirk_usb_handoff_xhci(struct pci_dev *pdev)
>   /* We're reading garbage from the controller */
>   dev_warn(>dev,
>"xHCI controller failing to respond");
> - return;
> + goto out;

If "out" is only used here, why not iounmap and return directly here?

>   }
>  
>   if (!ext_cap_offset)
> @@ -1062,6 +1062,7 @@ hc_init:
>XHCI_MAX_HALT_USEC, val);
>   }
>  
> +out:
>   iounmap(base);
>  }
>  

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Re: (4.3.0) r8152: deadlock related to runtime suspend?

[Lu Baolu]

On 12/07/2015 05:37 PM, Peter Wu wrote:
> On Mon, Dec 07, 2015 at 05:11:50PM +0800, Lu Baolu wrote:
>> Hi Peter,
>>
>> Have you ever tried disabling auto-pm? Did things go smoothly if auto-pm is 
>> disabled?
>>
>> I always disable usb auto-pm in below way.
>>
>> # echo on | tee /sys/bus/usb/devices/*/power/control
>> # echo on > /sys/bus/pci/devices//power/control
>>
>> Thanks,
>> Baolu
> Hi Baolu,
>
> The deadlock does not seem to occur with auto-PM disabled, but that is a
> workaround for the issue. The hang can always be reproduced under this
> test:
>
>  - Start a QEMU VM, passing through the USB adapter

I would suggest you to start with bare metal.

When you pass through the host controller to a guest VM, you
probably use IOMMU unit to let hardware access the memory
directly, but things like pci configure space access, interrupt and
IO port access still rely on QEMU. This introduces a lot of complexities.

Thanks,
Baolu

>  - This VM boots to a busybox shell with no other services running or
>udev magic (to reduce interference).
>  - Enable runtime PM for all devices by default (see script below)
>  - From the console, invoke "ip link set eth1 up" (eth0 is a virtio
>adapter).
>
> # somewhere in /init after mounting filesystems
> echo /sbin/hotplug > /proc/sys/kernel/hotplug
> echo auto | tee  /sys/bus/pci/devices/*/power/control \
> /sys/bus/usb/devices/*/power/control >/dev/null
>
> #!/bin/sh
> # /sbin/hotplug
> path="/sys/$DEVPATH/power/control"
> [ -e "$path" ] || return
> newval=auto
> read status < "$path"
> if [ "x$status" != "x$newval" ]; then
> echo "$DEVPATH: $status -> $newval" >/dev/kmsg
> echo $newval > "$path"
> fi
>
> With "auto", the ip command hangs (a trace can be found on the bottom of
> this mail). With "on", it does not.
>
> If I keep a loop spinning that invokes `ethtool eth1`, the command
> returns immediately without issues (presumably because the device is not
> suspended through runtime PM).
>
> Under some circumstances I get a lockdep warning (when trying to bring
> an interface down if I remember correctly). Its trace can be found on
> the bottom of this mail.
>
> I'll keep testing. For the lockdep warning, my initial guess is that
> calling schedule_delayed_work_sync under tp->lock is a bad idea because
> scheduled work can execute and try to claim tp->lock too.
>
> Maybe there are two different lockup cases here, I'll keep testing.
>
> Kind regards,
> Peter
>
>> On 12/05/2015 06:59 PM, Peter Wu wrote:
>>> Hi,
>>>
>>> I rarely use a Realtek USB 3.0 Gigabit Ethernet adapter (vid/pid
>>> 0bda:8153), but when I did last night, it resulted in a lockup of
>>> processes doing networking ("ip link", "ping", "ethtool", ...).
>>>
>>> A (few) minute(s) before that event, I noticed that there was no network
>>> connectivity (ping hung) which was somehow solved by invoking "ethtool
>>> eth1" (triggering runtime pm wakeup?). This same trick did not work at
>>> the next event. Invoking "ethtool eth1", "ip link", etc. hung completely
>>> and interrupt (^C) did not work at all.
>>>
>>> Since that did not work, I pulled the USB adapter and re-inserted it,
>>> hoping it would reset things. That did not work at all, there was a
>>> "usb disconnect" message, but no further driver messages.
>>>
>>> Fast forward an hour, and it has become a disaster. I have terminated
>>> and killed many programs via SysRq but am still unable to get a stable
>>> system that does not hang on network I/O. Even the suspend process
>>> fails so in the end I attempted to shutdown the system. After half an
>>> hour after getting the poweroff message, I issued SysRq + B to reboot
>>> (since SysRq + O did not shut down either).
>>>
>>> Attached are logs with various various backtraces from SysRq and failed
>>> suspend. Let me know if you need more information!
>>>
>>> By the way, often I have to rmmod xhci and re-insert it, otherwise
>>> plugging it in does not result in a detection. A USB 2.0 port does not
>>> have this problem (runtime PM is enabled for all devices). This is the
>>> USB 3.0 port:
>>>
>>> 02:00.0 USB controller [0c03]: NEC Corporation uPD720200 USB 3.0
>>> Host Controller [1033:0194] (rev 03)

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[PATCH v5 12/12] usb: doc: add document for xHCI DbC driver

[Lu Baolu]

Add Documentation/usb/xhci-dbc.txt. This document includes
development status and user guide for USB3 debug port.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/usb/xhci-dbc.txt | 350 +
 MAINTAINERS|   1 +
 drivers/usb/early/xhci-dbc.c   |   3 +
 3 files changed, 354 insertions(+)
 create mode 100644 Documentation/usb/xhci-dbc.txt

diff --git a/Documentation/usb/xhci-dbc.txt b/Documentation/usb/xhci-dbc.txt
new file mode 100644
index 000..564fd8f
--- /dev/null
+++ b/Documentation/usb/xhci-dbc.txt
@@ -0,0 +1,350 @@
+xHCI debug capability driver
+
+         Lu Baolu <baolu...@linux.intel.com>
+
+Last-updated: September 2015
+
+
+   Contents:
+   -
+   * What is xHCI DbC?
+   * Debug topologies
+   * Debug stacks
+   * Port Multiplexing
+   * Hardware initialization
+   * External reset
+   * Port reset
+   * Interrupt/DMA/Memory during early boot
+   * Endpoint STALL
+   * Debug device information
+   * How to use DbC early printk?
+   * Limitations
+
+   What is xHCI DbC?
+   -
+
+The xHCI Debugging Capability defined in section 7.6 of xHCI spec 1.1
+provides an optional functionality that enables low-level system debug
+over USB. It provides a means of connecting two systems where one system
+is a Debug Host and the other a Debug Target (System Under Test). The
+Debug Capability provides an interface that is completely independent
+of the xHCI interface. A Debug Target enumerates as a USB debug device
+to the Debug Host, allowing a Debug Host to access a Debug Target through
+the standard USB software stack.
+
+   Debug topologies
+   
+
+Multiple Debug Targets may be attached to a single Debug Host. Debug
+Targets may be connected to any downstream facing port below a Debug
+Host (i.e. anywhere in the fabric, root port or external hub puts).
+A Debug Target may only connect to a Debug Host through a Root Hub port
+of the target. That means connection of a Debug Target to a Debug Host
+through the ports of an external hub is not supported.
+
+Below is a typical connection between Debug Host and Debug target. Two
+Debug targets are connected to a single Debug host.
+
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+  || |
+  ||_|
+  |_
+|
+ ___|
+|   HUB  |  |  Debug Target  |
+||  ||
+| Superspeed hub |  |  xHC with DbC  |
+||  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+   Debug stacks
+   
+
+Below is a software stack diagram of both Debug Host and Debug Target.
+
+ 
+|   Debug Host   |  |  Debug Target  |
+||  ||
+|   debug App|  ||
+||  | system debug   |
+|   usb_debug|  | hooks  |
+||  ||
+|usbcore |  ||
+||  |debug capability|
+|xhci_hcd|  | driver |
+||  ||
+|xHC without DbC |  |  xHC with DbC  |
+|or DbC disabled |  | enabled|
+||  ||
+|P1|  |p2|  |P1|  |p2|
+|__|  |__|  |__|  |__|
+   | |
+   |_|
+
+
+   Port Multiplexing
+   -
+
+A debug port is always multiplexed with the first xHCI root hub port.
+Whenever debug capability is supported and enabled, and the first root
+hub port is detected to be connected to a downstream super-speed port
+of a Debug Host, the r

[PATCH v5 11/12] usb: serial: usb_debug: add support for dbc debug device

[Lu Baolu]

This patch add dbc debug device support in usb_debug driver.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Acked-by: Johan Hovold <jo...@kernel.org>
---
 drivers/usb/serial/usb_debug.c | 28 +---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/usb_debug.c b/drivers/usb/serial/usb_debug.c
index ca2fa5b..92f7e5c 100644
--- a/drivers/usb/serial/usb_debug.c
+++ b/drivers/usb/serial/usb_debug.c
@@ -32,7 +32,18 @@ static const struct usb_device_id id_table[] = {
{ USB_DEVICE(0x0525, 0x127a) },
{ },
 };
-MODULE_DEVICE_TABLE(usb, id_table);
+
+static const struct usb_device_id dbc_id_table[] = {
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+
+static const struct usb_device_id id_table_combined[] = {
+   { USB_DEVICE(0x0525, 0x127a) },
+   { USB_DEVICE(0x1d6b, 0x0004) },
+   { },
+};
+MODULE_DEVICE_TABLE(usb, id_table_combined);
 
 /* This HW really does not support a serial break, so one will be
  * emulated when ever the break state is set to true.
@@ -71,9 +82,20 @@ static struct usb_serial_driver debug_device = {
.process_read_urb = usb_debug_process_read_urb,
 };
 
+static struct usb_serial_driver dbc_device = {
+   .driver = {
+   .owner =THIS_MODULE,
+   .name = "xhci_dbc",
+   },
+   .id_table = dbc_id_table,
+   .num_ports =1,
+   .break_ctl =usb_debug_break_ctl,
+   .process_read_urb = usb_debug_process_read_urb,
+};
+
 static struct usb_serial_driver * const serial_drivers[] = {
-   _device, NULL
+   _device, _device, NULL
 };
 
-module_usb_serial_driver(serial_drivers, id_table);
+module_usb_serial_driver(serial_drivers, id_table_combined);
 MODULE_LICENSE("GPL");
-- 
2.1.4

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[PATCH v5 10/12] usb: xhci: dbc: add handshake between debug target and host

[Lu Baolu]

After DbC setup, debug target needs to wait until tty driver and
application (e.g. mincom) on debug taget start.  Otherwise, out
messages might be ignored.

This patch adds a ping/pong mechanism between debug target and
host. Debug target will be waiting there until user presses 'Y'
or 'y' in the tty application.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 27 +++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 6c24ba0..37c5c87 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,6 +32,9 @@
 static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
+static int early_xdbc_read(struct console *con, char *str, unsigned n);
+static void early_xdbc_write(struct console *con, const char *str, u32 n);
+
 #ifdef DBC_DEBUG
 #defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
 #defineMSG_MAX_LINE128
@@ -860,8 +863,12 @@ int __init early_xdbc_init(char *s)
 {
u32 bus = 0, dev = 0, func = 0;
unsigned long dbgp_num = 0;
+   char *ping = "Press Y to continue...\n";
+   char pong[64];
+   size_t size;
u32 offset;
int ret;
+   int retry = 20;
 
if (!early_pci_allowed())
return -EPERM;
@@ -904,6 +911,21 @@ int __init early_xdbc_init(char *s)
return ret;
}
 
+   while (retry > 0) {
+   early_xdbc_write(NULL, ping, strlen(ping));
+   size = early_xdbc_read(NULL, pong, 64);
+   if (size > 0) {
+   xdbc_trace("%s: pong message: %s\n", __func__, pong);
+   if (pong[0] == 'Y' || pong[0] == 'y')
+   break;
+   } else {
+   xdbc_trace("%s: pong message error %d\n",
+   __func__, size);
+   }
+
+   retry--;
+   }
+
return 0;
 }
 
@@ -1325,6 +1347,11 @@ int xdbc_bulk_write(const char *bytes, int size)
  * Start a bulk-in or bulk-out transfer, wait until transfer completion
  * or error. Return the count of actually transferred bytes or error.
  */
+static int early_xdbc_read(struct console *con, char *str, unsigned n)
+{
+   return xdbc_bulk_read(str, n, 0);
+}
+
 static void early_xdbc_write(struct console *con, const char *str, u32 n)
 {
int chunk, ret;
-- 
2.1.4

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[PATCH v5 07/12] usb: xhci: dbc: handle dbc-configured exit

[Lu Baolu]

DbC might exit configured state in some cases (refer to 7.6.4.4 in
xHCI spec 1.1). Software needs detect and clear this situation by
clearing DCCTRL.DCR and wait until the DbC configured before read
or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 28 
 1 file changed, 28 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index f59c80ef..c81df40 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1140,6 +1140,29 @@ static int xdbc_wait_until_bulk_done(struct xdbc_trb 
*trb, int loops)
return -EIO;
 }
 
+static int xdbc_wait_until_dbc_configured(void)
+{
+   int timeout = 0;
+   u32 reg;
+
+   /* Port exits configured state */
+   reg = readl(>xdbc_reg->control);
+   if (!(reg & CTRL_DRC))
+   return 0;
+
+   /* clear run change bit (RW1C) */
+   writel(reg | CTRL_DRC, >xdbc_reg->control);
+
+   do {
+   if (readl(>xdbc_reg->control) & CTRL_DCR)
+   return 0;
+
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1154,6 +1177,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EINVAL;
}
 
+   if (xdbc_wait_until_dbc_configured()) {
+   xdbc_trace("%s: hardware not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v5 06/12] usb: xhci: dbc: add bulk out and bulk in interfaces

[Lu Baolu]

This patch adds interfaces for bulk out and bulk in ops. These
interfaces could be used to implement early printk bootconsole
or hook to various system debuggers.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 373 +++
 include/linux/usb/xhci-dbc.h |  30 
 2 files changed, 403 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 6855048..f59c80ef 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -219,11 +219,21 @@ static void xdbc_dbg_dump_data(char *str)
xdbc_dbg_dump_string("String Descriptor:");
 }
 
+static void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str)
+{
+   xdbc_trace("DBC trb: %s\n", str);
+   xdbc_trace("@%016llx %08x %08x %08x %08x\n", (u64)__pa(trb),
+   le32_to_cpu(trb->field[0]),
+   le32_to_cpu(trb->field[1]),
+   le32_to_cpu(trb->field[2]),
+   le32_to_cpu(trb->field[3]));
+}
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
 static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
+static inline void xdbc_dbg_dump_trb(struct xdbc_trb *trb, char *str) { }
 #endif /* DBC_DEBUG */
 
 /*
@@ -334,6 +344,7 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
static char in_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char out_ring_page[PAGE_SIZE] __aligned(PAGE_SIZE);
static char table_page[PAGE_SIZE] __aligned(PAGE_SIZE);
+   static char bulk_buf_page[PAGE_SIZE] __aligned(PAGE_SIZE);
 
switch (type) {
case XDBC_PAGE_EVENT:
@@ -348,6 +359,9 @@ static void *xdbc_get_page(dma_addr_t *dma_addr,
case XDBC_PAGE_TABLE:
virt = (void *)table_page;
break;
+   case XDBC_PAGE_BUFFER:
+   virt = (void *)bulk_buf_page;
+   break;
default:
return NULL;
}
@@ -694,6 +708,12 @@ static int xdbc_mem_init(void)
dev_info = cpu_to_le32((XDBC_DEVICE_REV << 16) | XDBC_PRODUCT_ID);
writel(dev_info, >xdbc_reg->devinfo2);
 
+   /* get and store the transfer buffer */
+   xdbcp->out_buf = xdbc_get_page(>out_dma,
+   XDBC_PAGE_BUFFER);
+   xdbcp->in_buf = xdbcp->out_buf + XDBC_MAX_PACKET;
+   xdbcp->in_dma = xdbcp->out_dma + XDBC_MAX_PACKET;
+
return 0;
 }
 
@@ -789,6 +809,9 @@ static int xdbc_start(void)
 
xdbc_trace("root hub port number %d\n", DCST_DPN(status));
 
+   xdbcp->in_ep_state = EP_RUNNING;
+   xdbcp->out_ep_state = EP_RUNNING;
+
xdbc_trace("DbC is running now, control 0x%08x\n",
readl(>xdbc_reg->control));
 
@@ -882,3 +905,353 @@ int __init early_xdbc_init(char *s)
 
return 0;
 }
+
+static void xdbc_queue_trb(struct xdbc_ring *ring,
+   u32 field1, u32 field2, u32 field3, u32 field4)
+{
+   struct xdbc_trb *trb, *link_trb;
+
+   trb = ring->enqueue;
+   trb->field[0] = cpu_to_le32(field1);
+   trb->field[1] = cpu_to_le32(field2);
+   trb->field[2] = cpu_to_le32(field3);
+   trb->field[3] = cpu_to_le32(field4);
+
+   xdbc_dbg_dump_trb(trb, "enqueue trb");
+
+   ++(ring->enqueue);
+   if (ring->enqueue >= >segment->trbs[TRBS_PER_SEGMENT - 1]) {
+   link_trb = ring->enqueue;
+   if (ring->cycle_state)
+   link_trb->field[3] |= cpu_to_le32(TRB_CYCLE);
+   else
+   link_trb->field[3] &= cpu_to_le32(~TRB_CYCLE);
+
+   ring->enqueue = ring->segment->trbs;
+   ring->cycle_state ^= 1;
+   }
+}
+
+static void xdbc_ring_doorbell(int target)
+{
+   writel(DOOR_BELL_TARGET(target), >xdbc_reg->doorbell);
+}
+
+static void xdbc_handle_port_status(struct xdbc_trb *evt_trb)
+{
+   u32 port_reg;
+
+   port_reg = readl(>xdbc_reg->portsc);
+
+   if (port_reg & PORTSC_CSC) {
+   xdbc_trace("%s: connect status change event\n", __func__);
+   writel(port_reg | PORTSC_CSC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PRC) {
+   xdbc_trace("%s: port reset change event\n", __func__);
+   writel(port_reg | PORTSC_PRC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_PLC) {
+   xdbc_trace("%s: port link status change event\n", __func__);
+   writel(

[PATCH v5 05/12] usb: xhci: dbc: add debug buffer

[Lu Baolu]

"printk" is not suitable for dbc debugging especially when console
is in usage. This patch adds a debug buffer in dbc driver and puts
the debug messages in this local buffer. The debug buffer could be
dumped whenever the console is not in use. This part of code will
not be visible unless DBC_DEBUG is defined.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 62 ++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 41ce116..6855048 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,8 +32,64 @@ static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = _stat;
 
 #ifdef DBC_DEBUG
-/* place holder */
-#definexdbc_trace  printk
+#defineXDBC_DEBUG_BUF_SIZE (PAGE_SIZE * 32)
+#defineMSG_MAX_LINE128
+static char xdbc_debug_buf[XDBC_DEBUG_BUF_SIZE];
+static void xdbc_trace(const char *fmt, ...)
+{
+   int i, size;
+   va_list args;
+   static int pos;
+   char temp_buf[MSG_MAX_LINE];
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   return;
+
+   memset(temp_buf, 0, MSG_MAX_LINE);
+   va_start(args, fmt);
+   vsnprintf(temp_buf, MSG_MAX_LINE - 1, fmt, args);
+   va_end(args);
+
+   i = 0;
+   size = strlen(temp_buf);
+   while (i < size) {
+   xdbc_debug_buf[pos] = temp_buf[i];
+   pos++;
+   i++;
+
+   if (pos >= XDBC_DEBUG_BUF_SIZE - 1)
+   break;
+   }
+}
+
+static void xdbc_dump_debug_buffer(void)
+{
+   int index = 0;
+   int count = 0;
+   char dump_buf[MSG_MAX_LINE];
+
+   xdbc_trace("The end of DbC trace buffer\n");
+   pr_notice("DBC debug buffer:\n");
+   memset(dump_buf, 0, MSG_MAX_LINE);
+
+   while (index < XDBC_DEBUG_BUF_SIZE) {
+   if (!xdbc_debug_buf[index])
+   break;
+
+   if (xdbc_debug_buf[index] == '\n' ||
+   count >= MSG_MAX_LINE - 1) {
+   pr_notice("DBC: @%08x %s\n", index, dump_buf);
+   memset(dump_buf, 0, MSG_MAX_LINE);
+   count = 0;
+   } else {
+   dump_buf[count] = xdbc_debug_buf[index];
+   count++;
+   }
+
+   index++;
+   }
+}
+
 static void xdbc_dbg_dump_regs(char *str)
 {
if (!xdbcp->xdbc_reg) {
@@ -165,6 +221,7 @@ static void xdbc_dbg_dump_data(char *str)
 
 #else
 static inline void xdbc_trace(const char *fmt, ...) { }
+static inline void xdbc_dump_debug_buffer(void) { }
 static inline void xdbc_dbg_dump_regs(char *str) { }
 static inline void xdbc_dbg_dump_data(char *str) { }
 #endif /* DBC_DEBUG */
@@ -819,6 +876,7 @@ int __init early_xdbc_init(char *s)
pr_notice("failed to setup xHCI DbC connection\n");
xdbcp->xhci_base = NULL;
xdbcp->xdbc_reg = NULL;
+   xdbc_dump_debug_buffer();
return ret;
}
 
-- 
2.1.4

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[PATCH v5 09/12] x86: early_printk: add USB3 debug port earlyprintk support

[Lu Baolu]

Add support for early printk by writing debug messages to the USB3
debug port. Users can use this type of early printk by specifying
kernel parameter of "earlyprintk=xdbc". This gives users a chance
of providing debug output.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 Documentation/kernel-parameters.txt |  1 +
 arch/x86/kernel/early_printk.c  |  5 +
 drivers/usb/early/xhci-dbc.c| 43 +
 include/linux/usb/xhci-dbc.h|  5 +
 4 files changed, 54 insertions(+)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index e6b6e056..dfce467 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1049,6 +1049,7 @@ bytes respectively. Such letter suffixes can also be 
entirely omitted.
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
earlyprintk=pciserial,bus:device.function[,baudrate]
+   earlyprintk=xdbc[xhciController#]
 
earlyprintk is useful when the kernel crashes before
the normal console is initialized. It is not enabled by
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 21bf924..ba4c471 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -373,6 +374,10 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
early_console_register(_dbgp_console, keep);
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   if (!strncmp(buf, "xdbc", 4) && !early_xdbc_init(buf + 4))
+   early_console_register(_xdbc_console, keep);
+#endif
 #ifdef CONFIG_HVC_XEN
if (!strncmp(buf, "xen", 3))
early_console_register(_console, keep);
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 344d93e..6c24ba0 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -10,6 +10,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include 
 #include 
 #include 
 #include 
@@ -1319,3 +1320,45 @@ int xdbc_bulk_write(const char *bytes, int size)
 
return ret;
 }
+
+/*
+ * Start a bulk-in or bulk-out transfer, wait until transfer completion
+ * or error. Return the count of actually transferred bytes or error.
+ */
+static void early_xdbc_write(struct console *con, const char *str, u32 n)
+{
+   int chunk, ret;
+   static char buf[XDBC_MAX_PACKET];
+   int use_cr = 0;
+
+   if (!xdbcp->xdbc_reg)
+   return;
+   memset(buf, 0, XDBC_MAX_PACKET);
+   while (n > 0) {
+   for (chunk = 0; chunk < XDBC_MAX_PACKET && n > 0;
+str++, chunk++, n--) {
+   if (!use_cr && *str == '\n') {
+   use_cr = 1;
+   buf[chunk] = '\r';
+   str--;
+   n++;
+   continue;
+   }
+   if (use_cr)
+   use_cr = 0;
+   buf[chunk] = *str;
+   }
+   if (chunk > 0) {
+   ret = xdbc_bulk_write(buf, chunk);
+   if (ret < 0)
+   break;
+   }
+   }
+}
+
+struct console early_xdbc_console = {
+   .name = "earlyxdbc",
+   .write =early_xdbc_write,
+   .flags =CON_PRINTBUFFER,
+   .index =-1,
+};
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 289ba58..a556eb8 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -216,4 +216,9 @@ struct xdbc_state {
 #definexdbc_read64(regs)   xhci_read_64(NULL, (regs))
 #definexdbc_write64(val, regs) xhci_write_64(NULL, (val), (regs))
 
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+extern int early_xdbc_init(char *s);
+extern struct console early_xdbc_console;
+#endif /* CONFIG_EARLY_PRINTK_XDBC */
+
 #endif /* __LINUX_XHCI_DBC_H */
-- 
2.1.4

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[PATCH v5 08/12] usb: xhci: dbc: handle endpoint stall

[Lu Baolu]

In case of endpoint stall, software is able to detect the situation
by reading DCCTRL.HIT or DCCTRL.HOT bits. DbC follows the normal USB
framework to handle endpoint stall. When software detects endpoint
stall situation, it should wait until endpoint is recovered before
read or write oprations.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 36 
 1 file changed, 36 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index c81df40..344d93e 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1163,6 +1163,37 @@ static int xdbc_wait_until_dbc_configured(void)
return -ETIMEDOUT;
 }
 
+static int xdbc_wait_until_epstall_cleared(bool read)
+{
+   int timeout = 0;
+
+   if (read) {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HIT)) {
+   xdbcp->in_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->in_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   } else {
+   do {
+   if (!(readl(>xdbc_reg->control) & CTRL_HOT)) {
+   xdbcp->out_ep_state = EP_RUNNING;
+
+   return 0;
+   }
+
+   xdbcp->out_ep_state = EP_HALTED;
+   xdbc_udelay(10);
+   } while (timeout++ < XDBC_LOOPS);
+   }
+
+   return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
u64 addr;
@@ -1182,6 +1213,11 @@ static int xdbc_bulk_transfer(void *data, int size, int 
loops, bool read)
return -EPERM;
}
 
+   if (xdbc_wait_until_epstall_cleared(read)) {
+   xdbc_trace("%s: endpoint not ready\n", __func__);
+   return -EPERM;
+   }
+
ring = (read ? >in_ring : >out_ring);
trb = ring->enqueue;
cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v5 03/12] usb: xhci: dbc: probe and setup xhci debug capability

[Lu Baolu]

xHCI debug capability (DbC) is an optional functionality provided
by an xHCI host controller. Software learns this capability by
walking through the extended capability list in mmio of the host.

This patch introduces the code to probe and initialize the debug
capability hardware during early boot. With hardware initialization
done, the debug target (system under debug which has DbC enabled)
will present a debug device through the debug port. The debug device
is fully compliant with the USB framework and provides the equivalent
of a very high performance (USB3) full-duplex serial link between the
debug host and target.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 MAINTAINERS  |   7 +
 arch/x86/Kconfig.debug   |  12 +
 drivers/usb/early/Makefile   |   1 +
 drivers/usb/early/xhci-dbc.c | 774 +++
 include/linux/usb/xhci-dbc.h | 187 +++
 5 files changed, 981 insertions(+)
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 include/linux/usb/xhci-dbc.h

diff --git a/MAINTAINERS b/MAINTAINERS
index cba790b..9fb7c2f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11266,6 +11266,13 @@ S: Supported
 F: drivers/usb/host/xhci*
 F: drivers/usb/host/pci-quirks*
 
+USB XHCI DEBUG PORT
+M:     Lu Baolu <baolu...@linux.intel.com>
+L: linux-usb@vger.kernel.org
+S: Supported
+F: drivers/usb/early/xhci-dbc.c
+F: include/linux/usb/xhci-dbc.h
+
 USB ZD1201 DRIVER
 L: linux-wirel...@vger.kernel.org
 W: http://linux-lc100020.sourceforge.net
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 137dfa9..e450f88 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -65,6 +65,18 @@ config EARLY_PRINTK_EFI
  This is useful for kernel debugging when your machine crashes very
  early before the console code is initialized.
 
+config EARLY_PRINTK_XDBC
+   bool "Early printk via xHCI debug port"
+   depends on EARLY_PRINTK && PCI
+   ---help---
+ Write kernel log output directly into the xHCI debug port.
+
+ This is useful for kernel debugging when your machine crashes very
+ early before the console code is initialized. For normal operation
+ it is not recommended because it looks ugly and doesn't cooperate
+ with klogd/syslogd or the X server. You should normally N here,
+ unless you want to debug such a crash.
+
 config X86_PTDUMP_CORE
def_bool n
 
diff --git a/drivers/usb/early/Makefile b/drivers/usb/early/Makefile
index 24bbe51..2db5906 100644
--- a/drivers/usb/early/Makefile
+++ b/drivers/usb/early/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_EARLY_PRINTK_DBGP) += ehci-dbgp.o
+obj-$(CONFIG_EARLY_PRINTK_XDBC) += xhci-dbc.o
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
new file mode 100644
index 000..254a0a8
--- /dev/null
+++ b/drivers/usb/early/xhci-dbc.c
@@ -0,0 +1,774 @@
+/**
+ * xhci-dbc.c - xHCI debug capability driver
+ *
+ * Copyright (C) 2015 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ * Some code shared with EHCI debug port and xHCI driver.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+#include "../host/xhci.h"
+
+#defineXDBC_PROTOCOL   1   /* GNU Remote Debug Command Set 
*/
+#defineXDBC_VENDOR_ID  0x1d6b  /* Linux Foundation 0x1d6b */
+#defineXDBC_PRODUCT_ID 0x0004  /* __le16 idProduct; device 
0004 */
+#defineXDBC_DEVICE_REV 0x0010  /* 0.10 */
+
+static struct xdbc_state xdbc_stat;
+static struct xdbc_state *xdbcp = _stat;
+
+#ifdef DBC_DEBUG
+/* place holder */
+#definexdbc_trace  printk
+static void xdbc_dbg_dump_regs(char *str)
+{
+   if (!xdbcp->xdbc_reg) {
+   xdbc_trace("register not mapped\n");
+   return;
+   }
+
+   xdbc_trace("XDBC registers: %s\n", str);
+   xdbc_trace("  Capability: %08x\n",
+   readl(>xdbc_reg->capability));
+   xdbc_trace("  Door bell: %08x\n",
+   readl(>xdbc_reg->doorbell));
+   xdbc_trace("  Event Ring Segment Table Size: %08x\n",
+   readl(>xdbc_reg->ersts));
+   xdbc_trace("  Event Ring Segment Table Base Address: %16llx\n",
+   xdbc_read64(>xdbc_reg->erstba));
+   xdbc_trace("  Event Ring Dequeue Pointer: %16llx\n",
+   xdbc_read64(>xdbc_reg->erdp));
+   xdbc_trace("  Port status and control: %08x\n",
+   readl(&g

[PATCH v5 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu Baolu]

This patch adds a sysfs file for users to check 1) whether the debug
capability is implemented by hardware; 2) if supported, which state
does it stay at.

With a host that supports debug port, a file named "debug_port_state"
will be created under the device sysfs directory. Reading this file
will show users the state (disabled, enabled or configured) of the
debug port.

With a host that does NOT support debug port, "debug_port_state" file
won't be created.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd | 23 
 drivers/usb/host/Makefile  |  2 +-
 drivers/usb/host/xhci-ext-caps.h   |  5 ++
 drivers/usb/host/xhci-sysfs.c  | 65 ++
 drivers/usb/host/xhci.c|  4 ++
 drivers/usb/host/xhci.h|  4 ++
 6 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 drivers/usb/host/xhci-sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd 
b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
new file mode 100644
index 000..5d0a7d3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -0,0 +1,23 @@
+What:  /sys/bus/pci/drivers/xhci_hcd/.../debug_port_state
+Date:  November 2015
+KernelVersion: 4.4.0
+Contact:   Lu Baolu <baolu...@linux.intel.com>
+Description:
+   This file is designed for users to check the state of a
+   USB3 debug port. On a machine which supports USB3 debug
+   port, this file will be created. Reading this file will
+   show the state (disabled, enabled or configured) of the
+   debug port. On a machine that doesn't support USB3 debug
+   port, this file doesn't exist.
+
+   The state of a debug port could be:
+   1) disabled: The debug port is not enabled and the root
+   port has been switched to xHCI host as a normal
+   root port.
+   2) enabled: The debug port is enabled. The debug port
+   has been assigned to debug capability. The debug
+   capability is able to handle the control requests
+   defined in USB3 spec.
+   3) configured: The debug port has been enumerated by the
+   debug host as a debug device. The debug port is
+   in use now.
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index 65a06b4..aba2bf5 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -12,7 +12,7 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
-xhci-hcd-y += xhci-trace.o
+xhci-hcd-y += xhci-trace.o xhci-sysfs.o
 ifneq ($(CONFIG_USB_XHCI_MTK), )
xhci-hcd-y += xhci-mtk-sch.o
 endif
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 04ce6b1..c4b49c5 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -73,6 +73,11 @@
 #define XHCI_HLC   (1 << 19)
 #define XHCI_BLC   (1 << 20)
 
+/* Debug capability - section 7.6.8 */
+#define XHCI_DBC_DCCTRL0x20
+#define XHCI_DBC_DCCTRL_DCR(1 << 0)
+#define XHCI_DBC_DCCTRL_DCE(1 << 31)
+
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/
 #define XHCI_CMD_RUN   (1 << 0)
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 000..9feb727
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,65 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu...@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include 
+
+#include "xhci.h"
+
+#define GET_DBC_EXT_CAP_OFFSET(h)  \
+   xhci_find_next_ext_cap(&(h)->cap_regs->hc_capbase, \
+   0, XHCI_EXT_CAPS_DEBUG)
+
+static ssize_t debug_port_state_show(struct device *dev,
+   struct device_attribute *attr, char *buf)
+{
+   int count = 0, offset;
+   char*state;
+   void __iomem*dbc_base;
+   u32 dcctrl_reg;
+   struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+
+   offset = GET_DBC_EXT_CAP_OFFSET(xhci);
+   if (!offset)
+   return 0;
+
+   dbc_base = (void _

[PATCH v5 02/12] x86: fixmap: add permanent fixmap for xhci debug port

[Lu Baolu]

xHCI compatible USB3 host controller may provide debug capability
which enables low-level system debug over USB. In order to probing
this debug capability, Linux kernel needs to map and access the
mmio of the host controller during early boot.

This patch adds permenent fixmap pages in fixed_addresses table for
xHCI mmio access.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 arch/x86/include/asm/fixmap.h | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index f80d700..fbf452f 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -82,6 +82,10 @@ enum fixed_addresses {
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
FIX_OHCI1394_BASE,
 #endif
+#ifdef CONFIG_EARLY_PRINTK_XDBC
+   FIX_XDBC_BASE,
+   FIX_XDBC_END = FIX_XDBC_BASE + 15,
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE,  /* local (CPU) APIC) -- required for SMP or not */
 #endif
-- 
2.1.4

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[PATCH v5 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk

[Lu Baolu]

On Intel platforms, if the debug target is connected with debug
host, enabling DCE bit in command register leads to a port hung
state. In the hung state, the host system will not see a port
connected status bit set. Hence debug target fails to be probed.

The state could be resolved by performing a port reset to the
debug port from the host xHCI. This patch introduces this work
around.

Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 52 
 include/linux/usb/xhci-dbc.h |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 254a0a8..41ce116 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -255,6 +255,8 @@ static void __iomem *xdbc_map_pci_mmio(u32 bus,
xdbcp->bar = bar;
xdbcp->xhci_base = base;
xdbcp->xhci_length = sz64;
+   xdbcp->vendor = read_pci_config_16(bus, dev, func, PCI_VENDOR_ID);
+   xdbcp->device = read_pci_config_16(bus, dev, func, PCI_DEVICE_ID);
 
if (length)
*length = sz64;
@@ -638,6 +640,52 @@ static int xdbc_mem_init(void)
return 0;
 }
 
+static void xdbc_reset_debug_port_callback(int cap_offset, void *data)
+{
+   u8 major;
+   u32 val, port_offset, port_count;
+   u32 cap_length;
+   void __iomem *ops_reg;
+   void __iomem *portsc;
+   int i;
+
+   val = readl(xdbcp->xhci_base + cap_offset);
+   major = (u8) XHCI_EXT_PORT_MAJOR(val);
+
+   /* only reset super-speed port */
+   if (major != 0x3)
+   return;
+
+   val = readl(xdbcp->xhci_base + cap_offset + 8);
+   port_offset = XHCI_EXT_PORT_OFF(val);
+   port_count = XHCI_EXT_PORT_COUNT(val);
+   xdbc_trace("Extcap Port offset %d count %d\n",
+   port_offset, port_count);
+
+   cap_length = readl(xdbcp->xhci_base) & 0xff;
+   ops_reg = xdbcp->xhci_base + cap_length;
+
+   port_offset--;
+   for (i = port_offset; i < (port_offset + port_count); i++) {
+   portsc = ops_reg + 0x400 + i * 0x10;
+   val = readl(portsc);
+   /* reset the port if CCS bit is cleared */
+   if (!(val & 0x1))
+   writel(val | (1 << 4), portsc);
+   }
+}
+
+static void xdbc_reset_debug_port(void)
+{
+   xdbc_walk_excap(xdbcp->bus,
+   xdbcp->dev,
+   xdbcp->func,
+   XHCI_EXT_CAPS_PROTOCOL,
+   false,
+   xdbc_reset_debug_port_callback,
+   NULL);
+}
+
 /*
  * xdbc_start: start DbC
  *
@@ -656,6 +704,10 @@ static int xdbc_start(void)
return -ENODEV;
}
 
+   /* reset port to avoid bus hang */
+   if (xdbcp->vendor == PCI_VENDOR_ID_INTEL)
+   xdbc_reset_debug_port();
+
/* wait for port connection */
if (handshake(>xdbc_reg->portsc, PORTSC_CCS,
PORTSC_CCS, 500, 100) < 0) {
diff --git a/include/linux/usb/xhci-dbc.h b/include/linux/usb/xhci-dbc.h
index 153fb87..fc0ef9a 100644
--- a/include/linux/usb/xhci-dbc.h
+++ b/include/linux/usb/xhci-dbc.h
@@ -128,6 +128,8 @@ struct xdbc_state {
u32 dev;
u32 func;
u8  bar;
+   u16 vendor;
+   u16 device;
void __iomem*xhci_base;
size_t  xhci_length;
 #defineXDBC_PCI_MAX_BUSES  256
-- 
2.1.4

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[PATCH v5 00/12] usb: early: add support for early printk through USB3 debug port

[Lu Baolu]

Hi,

This patch series adds support for early printk through USB3 debug port.
USB3 debug port is described in xHCI specification as an optional extended
capability.

The first patch adds a file in sysfs, through which users can check
whether the debug capability is supported by a specific host controller,
and the hardware state.

Patch 2 to 10 add the driver for xHCI debug capability. It interfaces with
the register set and provides the required ops (read/write/control) to upper
layers. Early printk is one consumer of these ops. The hooks for early printk
are introduced in patch 9. This design is similar to what we have done in
drivers/usb/early/ehci-dbgp.c.

Patch 11 is a minor change to usb_debug module. This change is required to
bind usb_debug with the USB3 debug device.

Patch 12 is the design document and user guide.

Change log:
v1->v2:
(1) Patch 1 re-implemented. "debugfs" has been replaced with sysfs.
The scope reduced from all extended capabilities to debug port
specific.
(2) Patch 11 changed. Removed unnecessary .bulk_out_size setting.

v2->v3:
(1) Patch 11 got acked by Johan Hovold.

v3->v4:
(1) Patch 1 code refactored by using xhci_find_ext_cap_by_id() helper.
(2) Patch 3 "bus hung state" changed to "port hung state" in commit message.
(3) Patch 12 added verified platform information.

v4->v5:
(1) Patch 1 & 3 code refactored by using xhci_find_next_ext_cap() helper.
(2) Patch 12 updated with more user guide information.
(3) All patches rebased to the new usb-next branch which contains commit
d5ddcdf(xhci: rework xhci extended capability list parsing functions).

Lu Baolu (12):
  usb: xhci: add sysfs file for xHCI debug port
  x86: fixmap: add permanent fixmap for xhci debug port
  usb: xhci: dbc: probe and setup xhci debug capability
  usb: xhci: dbc: add support for Intel xHCI dbc quirk
  usb: xhci: dbc: add debug buffer
  usb: xhci: dbc: add bulk out and bulk in interfaces
  usb: xhci: dbc: handle dbc-configured exit
  usb: xhci: dbc: handle endpoint stall
  x86: early_printk: add USB3 debug port earlyprintk support
  usb: xhci: dbc: add handshake between debug target and host
  usb: serial: usb_debug: add support for dbc debug device
  usb: doc: add document for xHCI DbC driver

 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd |   23 +
 Documentation/kernel-parameters.txt|1 +
 Documentation/usb/xhci-dbc.txt |  350 +
 MAINTAINERS|8 +
 arch/x86/Kconfig.debug |   12 +
 arch/x86/include/asm/fixmap.h  |4 +
 arch/x86/kernel/early_printk.c |5 +
 drivers/usb/early/Makefile |1 +
 drivers/usb/early/xhci-dbc.c   | 1394 
 drivers/usb/host/Makefile  |2 +-
 drivers/usb/host/xhci-ext-caps.h   |5 +
 drivers/usb/host/xhci-sysfs.c  |   65 +
 drivers/usb/host/xhci.c|4 +
 drivers/usb/host/xhci.h|4 +
 drivers/usb/serial/usb_debug.c |   28 +-
 include/linux/usb/xhci-dbc.h   |  224 
 16 files changed, 2126 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 Documentation/usb/xhci-dbc.txt
 create mode 100644 drivers/usb/early/xhci-dbc.c
 create mode 100644 drivers/usb/host/xhci-sysfs.c
 create mode 100644 include/linux/usb/xhci-dbc.h

-- 
2.1.4

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Re: [PATCH 2/2] usb: pci-quirks: register USB mux found on Cherrytrail SOC

[Lu Baolu]

On 12/01/2015 09:32 PM, Heikki Krogerus wrote:
> Intel Braswell/Cherrytrail has an internal mux that shares
> one USB port between USB Device Controller and xHCI. The
> same mux is found on several SOCs from Intel, but only on
> a few Cherrytrail based platforms the OS is expected to
> configure it. Normally BIOS takes care of it.
>
> The driver for the mux is an "extcon" driver. With this we
> only register the mux if it's detected.
>
> Suggested-by: Lu Baolu <baolu...@linux.intel.com>
> Signed-off-by: Heikki Krogerus <heikki.kroge...@linux.intel.com>
> ---
>  drivers/usb/host/pci-quirks.c | 30 +-
>  1 file changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index f940056..4e3016a 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -16,6 +16,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  #include "pci-quirks.h"
>  #include "xhci-ext-caps.h"
>  
> @@ -1029,9 +1030,36 @@ static void quirk_usb_handoff_xhci(struct pci_dev 
> *pdev)
>   writel(val, base + ext_cap_offset + XHCI_LEGACY_CONTROL_OFFSET);
>  
>  hc_init:
> - if (pdev->vendor == PCI_VENDOR_ID_INTEL)
> + if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
>   usb_enable_intel_xhci_ports(pdev);
>  
> + /*
> +  * Initialize the internal mux that shares a port between USB
> +  * Device Controller and xHCI on platforms that have it.
> +  */
> +#define XHCI_INTEL_VENDOR_CAPS 192
> +#define XHCI_INTEL_USB_MUX_OFFSET 0x80d8
> + ext_cap_offset = xhci_find_next_cap_offset(base,
> + XHCI_HCC_PARAMS_OFFSET);
> + ext_cap_offset = xhci_find_ext_cap_by_id(base, ext_cap_offset,
> + XHCI_INTEL_VENDOR_CAPS);

Hi Heikki,

This helper has been replaced with xhci_find_next_ext_cap() in
commit d5ddcdf(xhci: rework xhci extended capability list parsing functions).

Need to fix this, otherwise it will not pass compile on top of usb-next.

Thanks,
Baolu

> + if (ext_cap_offset) {
> + struct intel_usb_mux *mux;
> + struct resource r;
> +
> + r.start = pci_resource_start(pdev, 0) +
> + XHCI_INTEL_USB_MUX_OFFSET;
> + r.end   = r.start + 8;
> + r.flags = IORESOURCE_MEM;
> +
> + mux = intel_usb_mux_register(>dev, );
> + if (IS_ERR(mux) && PTR_ERR(mux) == -ENOTSUPP)
> + dev_dbg(>dev, "USB mux not supported\n");
> + else if (IS_ERR(mux))
> + dev_err(>dev, "failed to register mux\n");
> + }
> + }
> +
>   op_reg_base = base + XHCI_HC_LENGTH(readl(base));
>  
>   /* Wait for the host controller to be ready before writing any

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