Re: uac2 configfs function seems to load incorrectly if loaded other particular functions

[Bjørn Mork]

Chris McClimans  writes:

> It looks like the ordering may be important.
> Configuring uac2 as your first function seems to resolve the issue.
> Must be a requirement documented somewhere, or an interesting bug. :)

It's a bug in uac2.  It statically sets the IAD bFirstInterface to 0
regardless of actual interface numbers being allocated to the function:

static struct usb_interface_assoc_descriptor iad_desc = {
.bLength = sizeof iad_desc,
.bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,

.bFirstInterface = 0,
.bInterfaceCount = 3,
.bFunctionClass = USB_CLASS_AUDIO,
.bFunctionSubClass = UAC2_FUNCTION_SUBCLASS_UNDEFINED,
.bFunctionProtocol = UAC_VERSION_2,
};

Compare this to other functions with an IAD.  They assign the IAD
bFirstInterface based on actual interface numbers allocated to the
function.  Example from f_ecm.c:

static struct usb_interface_assoc_descriptor
ecm_iad_descriptor = {
.bLength =  sizeof ecm_iad_descriptor,
.bDescriptorType =  USB_DT_INTERFACE_ASSOCIATION,

/* .bFirstInterface =   DYNAMIC, */
.bInterfaceCount =  2,  /* control + data */
.bFunctionClass =   USB_CLASS_COMM,
.bFunctionSubClass =USB_CDC_SUBCLASS_ETHERNET,
.bFunctionProtocol =USB_CDC_PROTO_NONE,
/* .iFunction = DYNAMIC */
};

..
static int
ecm_bind(struct usb_configuration *c, struct usb_function *f)
{
..

/* allocate instance-specific interface IDs */
status = usb_interface_id(c, f);
if (status < 0)
goto fail;
ecm->ctrl_id = status;
ecm_iad_descriptor.bFirstInterface = status;

ecm_control_intf.bInterfaceNumber = status;
ecm_union_desc.bMasterInterface0 = status;



Bjørn
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Re: uac2 configfs function seems to load incorrectly if loaded other particular functions

[Chris McClimans]

It looks like the ordering may be important.
Configuring uac2 as your first function seems to resolve the issue.
Must be a requirement documented somewhere, or an interesting bug. :)
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Re: uac2 configfs function seems to load incorrectly if loaded other particular functions

[Chris McClimans]

Thought it might be useful to include the kernel versions:

usb-host-arch$ uname -a
Linux viii 4.2.3-1-ARCH #1 SMP PREEMPT Sat Oct 3 18:52:50 CEST 2015
x86_64 GNU/Linux

usb-gadget-debian(beaglebone black)$ # uname -a
Linux beaglebone 4.1.12-ti-r26 #1 SMP PREEMPT Fri Oct 30 21:28:17 UTC
2015 armv7l GNU/Linux
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Re: usb: dwc2: regression during boot on Raspberry Pi

[Stefan Wahren]

Hi Stephen,

Am 08.11.2015 um 06:06 schrieb Stephen Warren:

On 11/07/2015 05:16 PM, Stefan Wahren wrote:

Hi,
[...]
   * phys (optional)
   * phy-names (optional)

So here are my questions:

How to fix the kernel oops in dwc2 driver?


Do you know exactly what causes the crash; you've bisected to the
specific commit, but I don't think mentioned why that commit causes an
issue.


The stacktrace in my initial mail shows a invalid paging request on 
hsotg->regs in dwc2_is_controller_alive() which is called by 
dwc2_handle_common_intr(). I must clarify the problem description. It's 
reproducable on Raspberry Pi since 09a75e857790, but the real problem 
seems to has been in the driver before. Looking at dwc2_driver_probe() 
that the irq responsable for dwc2_handle_common_intr is requested BEFORE 
hsotg->regs, hsotg->dr_mode and hsotg->lock are initialized.


I attached a patch which avoids this race by moving the request behind 
dwc2_lowlevel_hw_init(). Not sure about that, but the oops disappear.





Should we specify dr_mode = "host" for all Raspberry Pi variants in DT?


It's optional so the driver must work without it. However, that value
seems appropriate, so you could certainly add it.


That's not the first platform, which shows me that dr_mode is only 
optional for the case that the controller is really used for USB OTG. 
AFAIK the OTG ID pin of the Raspberry PI A and B are tied to GND. But 
the dwc2 driver doesn't know about that.





Which clock should be referenced by USB host in DT?

Do we need a USB PHY DT node and driver for bcm2835?


I don't think there's a separate PHY module in bcm2835 is there?
Certainly there is no documentation, binding, or driver for it that I'm
aware of. I haven't checked the RPi Foundation downstream kernel though.



I took a little deeper look into dwc2. According to 
dwc2_lowlevel_hw_init() the USB PHY is required and clk is optional. I'm 
confused :-(


Here is the draft for avoiding the oops:

--->8
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 5859b0f..0e80087 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -341,20 +341,6 @@ static int dwc2_driver_probe(struct platform_device 
*dev)

if (retval)
return retval;

-   irq = platform_get_irq(dev, 0);
-   if (irq < 0) {
-   dev_err(>dev, "missing IRQ resource\n");
-   return irq;
-   }
-
-   dev_dbg(hsotg->dev, "registering common handler for irq%d\n",
-   irq);
-   retval = devm_request_irq(hsotg->dev, irq,
- dwc2_handle_common_intr, IRQF_SHARED,
- dev_name(hsotg->dev), hsotg);
-   if (retval)
-   return retval;
-
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
hsotg->regs = devm_ioremap_resource(>dev, res);
if (IS_ERR(hsotg->regs))
@@ -389,6 +375,20 @@ static int dwc2_driver_probe(struct platform_device 
*dev)


dwc2_set_all_params(hsotg->core_params, -1);

+   irq = platform_get_irq(dev, 0);
+   if (irq < 0) {
+   dev_err(>dev, "missing IRQ resource\n");
+   return irq;
+   }
+
+   dev_dbg(hsotg->dev, "registering common handler for irq%d\n",
+   irq);
+   retval = devm_request_irq(hsotg->dev, irq,
+ dwc2_handle_common_intr, IRQF_SHARED,
+ dev_name(hsotg->dev), hsotg);
+   if (retval)
+   return retval;
+
retval = dwc2_lowlevel_hw_enable(hsotg);
if (retval)
return retval;

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CP2110 - no serial device created

[Martin Kozelský]

Hi, I have trouble with CP2110 chip (USB-to-serial converter) in kernel,
no /dev/ttyUSBx device created after connection.

I reported this bug https://bugzilla.kernel.org/show_bug.cgi?id=107501

Thanks

Martin Kozelsky
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Re: [PATCH v5 1/5] gadget: Introduce the notifier functions

[Baolin Wang]

On 7 November 2015 at 00:56, Greg KH  wrote:
> On Fri, Nov 06, 2015 at 07:35:10PM +0800, Baolin Wang wrote:

>>  #ifdef   CONFIG_HAS_DMA
>> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
>> index c14a69b..755e8bc 100644
>> --- a/include/linux/usb/gadget.h
>> +++ b/include/linux/usb/gadget.h
>> @@ -609,6 +609,8 @@ struct usb_gadget {
>>   unsignedout_epnum;
>>   unsignedin_epnum;
>>   struct usb_otg_caps *otg_caps;
>> + struct raw_notifier_headnh;
>> + struct mutexlock;
>
> You have to document what this lock protects.

OK.

>
>
>>
>>   unsignedsg_supported:1;
>>   unsignedis_otg:1;
>> @@ -1183,6 +1185,22 @@ extern void usb_gadget_unmap_request(struct 
>> usb_gadget *gadget,
>>
>>  
>> /*-*/
>>
>> +/**
>> + * Register a notifiee to get notified by any attach status changes from
>> + * the usb gadget
>> + */
>
> kerneldoc does not belong in a .h file.
>

I'll remove the comments.

> And the kbuild system found lots of problems with this series, please
> fix those at the very least :(

I'm sorry for that, I'll check the patches again. Thanks for your comments.

>
> thanks,
>
> greg k-h



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Re: [PATCH v5 0/5] usb/gadget: independent registration of gadgets and gadget drivers

[Maxime Ripard]

Hi Ruslan,

On Mon, Nov 02, 2015 at 06:44:00PM +0200, Ruslan Bilovol wrote:
> >> This patchset adds independent registration of gadgets
> >> and gadget drivers to udc-core. This is very useful for
> >> built-in modules into kernel case since it's possible
> >> situation that gadget driver is probing at a time
> >> when no gadgets are registered in udc-core.
> >> In this case instead of silently failing without
> >> of any attempt to recover, with independent registration
> >> of gadgets and gadget drivers there is no matter
> >> in which order gadgets and gadget drivers are
> >> probed/registered.
> >>
> >> This patch has side-effect on gadget drivers that had
> >> __init/__exit attributes on some paths like bind/unbind
> >> and (since bind/unbind may happen at any time) should
> >> not use them now. This is covered by forth patch
> >>
> >
> > Has there been any progress on these patches? They're fixing some real
> > issue that we're seeing, and it seems to both work quite well and not
> > generate a lot of pushback.
> 
> This patch series has stack on review due to different views
> on checking input parameters of externally visible function.
> 
> I see there is no any way to get these patches accepted other
> than skip checking validity of some input parameters as
> was pointed by Alan, although I disagree with it.
> 
> I will post updated patch series later

Great, thanks a lot!

Maxime

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Embedded Linux, Kernel and Android engineering
http://free-electrons.com


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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 
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 
Signed-off-by: Zhuang Jin Can 
---
 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 
+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 
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 @@ 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 

[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 
---
 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: Broken usb stick after plug it on an usb port?

[Javier Barroso]

Hello,

On Fri, Nov 6, 2015 at 12:42 AM, Javi Barroso  wrote:
> Hello,
>
> El 6 de noviembre de 2015 0:28:40 CET, Greg KH  escribió:
>>On Thu, Nov 05, 2015 at 06:03:15PM +0100, Javier Barroso wrote:
>>> Hello,
>>>
>>> I have a usb stick which was (apparently) broken after plug it on a
>>> usb port on my laptop [1]
>>
>>What do you mean exactly by "broken"?
>>
> USB stick owner tell me about the stick was working about 5 years more or 
> less without any problem with her windows laptop. She used this stick to 
> order print  some picture last week in a paper shop (other computer 
> different) and it worked fine.
>
> The first time that I plugged the stick on my laptop, it was not recognized 
> any more. No windows recognize, no linux, no apple.
>
> So the stick is currently broken
>
>>> My sequence of operation is attached at kern.log-commented.gz
>>>
>>> This laptop have a port which "Anytime USB Charge (see inside
>>>
>>http://www.shopfujitsu.com/www/content/products/notebooks/notebooks.php?products/notebooks/features_benefits/ah572_features_benefits)",
>>> but it is disabled on BIOS (so there should not be a problem)
>>>
>>> stick owner tell me about this stick was working before I plug it on
>>my laptop.
>>>
>>> Is it possible that my laptop kill/broke usb sticks ? I think this is
>>> the second time that such thing happens.
>>
>>Sounds like a really messed up USB port, but note, software can not
>>"break" any USB device, there is nothing for it to control that can
>>harm
>>anything.
>
> How can I check USB ports on my laptop?
>
Finally I check it with a Multimeter, and 5.04 was the voltage (all
ports on the laptop have the same voltage). I made the test while the
laptop was not battery charging. Maybe I should repeat such test
charging the battery.

Regard
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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 
Acked-by: Johan Hovold 
---
 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 
---
 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 
+
+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 root hub port 

[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 
---
 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 
---
 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 
---
 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 
---
 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 
+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 
+ * 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(>xdbc_reg->portsc));
+   xdbc_trace("  Debug Capability Context Pointer: %16llx\n",

[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 
---
 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 
---
 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(port_reg | PORTSC_PLC, >xdbc_reg->portsc);
+   port_reg = readl(>xdbc_reg->portsc);
+   }
+
+   if (port_reg & PORTSC_CEC) {
+   xdbc_trace("%s: config error change\n", __func__);
+   writel(port_reg | PORTSC_CEC, 

[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 
---
 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 
---
 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 
---
 .../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 
+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 
+ *
+ * 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 

[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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