On Thu, May 14, 2015 at 02:25:39PM +0000, Golmer Palmer wrote: > Hi, > I suggest some changes in the USB HID support of the Linux Gadget kernel > framework. > > The problem is that several Keyboard and Mouse implementations using > this > framework are in fact fully compatible with BOOT mode. They announce in > the descriptor as "Boot Interface Subclass", but they don't work with > BIOSes, KVMs and other simple USB implementations because the lack of > Get_Protocol() & Set_Protocol() functions. > > Here the info about the specifications: > > - Documentation about USB HID Interfaces: > http://www.usb.org/developers/hidpage/HID1_11.pdf > > - Page 73, Appendix F: Legacy Keyboard Implementation: > Any boot device can work as Legacy if it can change to BOOT mode. > So, this assumes that when the device is initialized it isn't in the > boot mode, but in the report mode. > > - Page 78, Appendix G: HID Request Support Requirements: > If the Report Descriptor of the device is fully compatible with the > BOOT mode, then the only remaining requirement is the implementation > of the Get_Protocol and Set_Protocol functions. > > - Page 54: 7.2.5 Get_Protocol Request / 7.2.6 Set_Protocol Request > The correct implementation of these functions are change the status > and report the status, that is a binary value > (0=Boot Protocol, 1=Report Protocol). > > Problem: These functions are miss unimplemented in the kernel... > > See file "/drivers/usb/gadget/function/f_hid.c" > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/ > drivers/usb/gadget/function/f_hid.c?id=refs/tags/v4.1-rc3 > > Inside the function: > "static int hidg_setup(struct usb_function *f, > const struct usb_ctrlrequest *ctrl)" > the call to set_protocol and get_protocol raises "stall" returning > NON_SUPPORTED. > > Then the solution for solving this problem is always change from Report > to Boot, and viceversa. Implementing a binary value returned by > get_protocol (at initialization the correct value is "1"=Report mode). > > I suggest that someone responsible of this framework implement this > change. > I feel it be easy to do, and I hope s/he can do it soon. you can implement it too and send a patch to us. Patches are always welcome. regards -- balbi
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