Hi, On 11/06/2017 04:00 PM, Greg Kroah-Hartman wrote: > On Mon, Nov 06, 2017 at 08:35:41AM +0800, Lu Baolu wrote: >> Hi, >> >> On 11/03/2017 02:27 PM, Greg Kroah-Hartman wrote: >>> On Fri, Nov 03, 2017 at 08:45:46AM +0800, Lu Baolu wrote: >>>> Hi, >>>> >>>> On 11/03/2017 12:51 AM, Greg Kroah-Hartman wrote: >>>>> On Thu, Nov 02, 2017 at 12:38:57PM +0200, Felipe Balbi wrote: >>>>>>> Hi, >>>>>>> >>>>>>> Greg Kroah-Hartman <gre...@linuxfoundation.org> writes: >>>>>>>>>>> Greg Kroah-Hartman <gre...@linuxfoundation.org> writes: >>>>>>>>>>>>>>>>> xHCI compatible USB host controllers(i.e. super-speed USB3 >>>>>>>>>>>>>>>>> controllers) >>>>>>>>>>>>>>>>> can be implemented with the Debug Capability(DbC). It >>>>>>>>>>>>>>>>> presents a debug >>>>>>>>>>>>>>>>> device which is fully compliant with the USB framework and >>>>>>>>>>>>>>>>> provides the >>>>>>>>>>>>>>>>> equivalent of a very high performance full-duplex serial >>>>>>>>>>>>>>>>> link. The debug >>>>>>>>>>>>>>>>> capability operation model and registers interface are >>>>>>>>>>>>>>>>> defined in 7.6.8 >>>>>>>>>>>>>>>>> of the xHCI specification, revision 1.1. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> The DbC debug device shares a root port with the xHCI host. >>>>>>>>>>>>>>>>> By default, >>>>>>>>>>>>>>>>> the debug capability is disabled and the root port is >>>>>>>>>>>>>>>>> assigned to xHCI. >>>>>>>>>>>>>>>>> When the DbC is enabled, the root port will be assigned to >>>>>>>>>>>>>>>>> the DbC debug >>>>>>>>>>>>>>>>> device, and the xHCI sees nothing on this port. This >>>>>>>>>>>>>>>>> implementation uses >>>>>>>>>>>>>>>>> a sysfs node named <dbc> under the xHCI device to manage the >>>>>>>>>>>>>>>>> enabling >>>>>>>>>>>>>>>>> and disabling of the debug capability. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> When the debug capability is enabled, it will present a debug >>>>>>>>>>>>>>>>> device >>>>>>>>>>>>>>>>> through the debug port. This debug device is fully compliant >>>>>>>>>>>>>>>>> with the >>>>>>>>>>>>>>>>> USB3 framework, and it can be enumerated by a debug host on >>>>>>>>>>>>>>>>> the other >>>>>>>>>>>>>>>>> end of the USB link. As soon as the debug device is >>>>>>>>>>>>>>>>> configured, a TTY >>>>>>>>>>>>>>>>> serial device named /dev/ttyDBC0 will be created. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> One use of this link is running a login service on the debug >>>>>>>>>>>>>>>>> target. >>>>>>>>>>>>>>>>> Hence it can be remote accessed by a debug host. Another use >>>>>>>>>>>>>>>>> case can >>>>>>>>>>>>>>>>> probably be found in servers. It provides a peer-to-peer USB >>>>>>>>>>>>>>>>> link >>>>>>>>>>>>>>>>> between two host-only machines. This provides a reasonable >>>>>>>>>>>>>>>>> out-of-band >>>>>>>>>>>>>>>>> communication method between two servers. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Signed-off-by: Lu Baolu <baolu...@linux.intel.com> >>>>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>>>> .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd | 25 + >>>>>>>>>>>>>>>>> drivers/usb/host/Kconfig | 9 + >>>>>>>>>>>>>>>>> drivers/usb/host/Makefile | 5 + >>>>>>>>>>>>>>>>> drivers/usb/host/xhci-dbgcap.c | 1016 >>>>>>>>>>>>>>>>> ++++++++++++++++++++ >>>>>>>>>>>>>>>>> drivers/usb/host/xhci-dbgcap.h | 247 >>>>>>>>>>>>>>>>> +++++ >>>>>>>>>>>>>>>>> drivers/usb/host/xhci-dbgtty.c | 586 >>>>>>>>>>>>>>>>> +++++++++++ >>>>>>>>>>>>>>>>> drivers/usb/host/xhci-trace.h | 60 ++ >>>>>>>>>>>>>>>>> drivers/usb/host/xhci.c | 10 + >>>>>>>>>>>>>>>>> drivers/usb/host/xhci.h | 1 + >>>>>>>>>>>>>>>>> 9 files changed, 1959 insertions(+) >>>>>>>>>>>>>>>>> create mode 100644 >>>>>>>>>>>>>>>>> Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd >>>>>>>>>>>>>>>>> create mode 100644 drivers/usb/host/xhci-dbgcap.c >>>>>>>>>>>>>>>>> create mode 100644 drivers/usb/host/xhci-dbgcap.h >>>>>>>>>>>>>>>>> create mode 100644 drivers/usb/host/xhci-dbgtty.c >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>> [snip] >>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> +#define DBC_VENDOR_ID 0x1d6b /* >>>>>>>>>>>>>>>>> Linux Foundation 0x1d6b */ >>>>>>>>>>>>>>>>> +#define DBC_PRODUCT_ID 0x0004 /* >>>>>>>>>>>>>>>>> device 0004 */ >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>> The DbC (xHCI DeBug Capability) is an optional functionality in >>>>>>>>>>>>>>> some xHCI host controllers. It will present a super-speed debug >>>>>>>>>>>>>>> device through the debug port after it is enabled. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> The DbC register set defines an interface for system software >>>>>>>>>>>>>>> to specify the vendor id and product id of the debug device. >>>>>>>>>>>>>>> These two values will be presented by the debug device in its >>>>>>>>>>>>>>> device descriptor idVendor and idProduct fields. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Microsoft Windows have a well established protocol for >>>>>>>>>>>>>>> debugging over DbC. And it assigns below values for its use. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> USB\VID_045E&PID_062D.DeviceDesc="Microsoft USB Debug Target" >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> I'm going to use 0x1d6b/0x0004 value pair for DbC use in >>>>>>>>>>>>>>> Linux. Do you approve me to do so? >>>>>>>>>>>>> No. Why can't you use the same ids as Windows? This is >>>>>>>>>>>>> implementing >>>>>>>>>>>>> the same protocol, right? >>>>>>>>>>> the protocol running on top is 100% vendor specific. More than >>>>>>>>>>> likely, >>>>>>>>>>> we would just run kgdb on top of this, right? We really don't >>>>>>>>>>> support >>>>>>>>>>> microsoft's debug architecture. >>>>>>>>> Ah, I didn't know about the protocol specifics here, if it is >>>>>>>>> vendor-specific, then yes, we need our own id. >>>>>>> Great, thanks :-) >>>>>>> >>>>>>> Let us know which one we're allowed to use and I'm sure Baolu can respin >>>>>>> the patch in no time. >>>>> Can I get a "full" description of what string this device id will >>>>> reference? Is it "Linux USB Debug Target" or something else? >>>>> >>>> Current manufacturer and product strings are set like this. >>>> >>>> +#define DBC_STRING_MANUFACTURER "Linux" >>>> +#define DBC_STRING_PRODUCT "Remote GDB" >>>> >>>> These are also place holders. We can change them to more meaningful >>>> strings. >>> As the vendor id is assigned to "Linux Foundation" can we change that >>> string please? >>> >>> And why not match what Microsoft does here, "USB Debug Target" makes >>> more sense than "Remote GDB", right? >>> >>> If so, please use device id 0x0010, I've reserved that for the driver >>> now. >>> >> I will change the strings and use the allocated product id. >> Thank you very much. >> >> Another DbC usage is to enable DbC during early boot time, >> and run GDB protocol data or early printk message over it. >> The early printk implementation has been merged in 4.12-rc1. >> >> commit aeb9dd1 <usb/early: Add driver for xhci debug capability> >> >> In this code, the DbC product id is still a place holder (0x0004). >> I am really sorry. I should apply a valid product id from you during >> the code review time. But I forgot it since almost all attention was >> paid to early driver itself at that time. >> >> We could use the same ID as you allocated here or, preferably, >> use a different ID since we're dealing with different functionality. > A different one would be best, please give me a good device string to > use and I will assign you a new ID, probably 0011. Also send a patch > now for this please. >
Thanks, Greg. How about below strings: Manufacturer: Linux Foundation Product: Linux USB GDB Target I will send out the patches soon. Best regards, Lu Baolu -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
