Hi, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> writes: >> >>>> > >> Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> 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.lu@xxxxxxxxxxxxxxx> >> >>>>>>> > >> >> > --- >> >>>>>>> > >> >> > .../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? I agree. It just happens to talk remote GDB protocol through KGDB, but we could run KDB directly or, even, come up with a new protocol. > If so, please use device id 0x0010, I've reserved that for the driver > now. thanks Greg -- balbi
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