I just found bugzilla bug #70181 which is the same problem as I describe but seen with a QPAD MK-85 keyboard. I will add my findings to that bug. On Fri, Aug 8, 2014 at 4:11 PM, Fredrik Hallenberg <megahallon@xxxxxxxxx> wrote: > Hi, > > On my Corsair K70 keyboard, when pressing some key and then the > backslash key (KEY_BACKSLASH) in rapid succession the backslash > character will be repeated three times. This bug has been mentioned on > this list before (by Norbert Veber on the 24th of februrary) but there > was no responses, also Norbert consider it a problem with Corsair > keyboards but as I describe below I feel it is more of a general > problem in the HID input code. > > This bug is discussed on the Corsair forums, but it seems the exact > same thing also happens with Gigabyte Osmium and QPAD MK85, possibly > it is a problem on all keyboards supporting n-key rollover. > > I believe the root cause of this is that the keyboard reports all keys > including both HID keys 0x31 and 0x32 which are both mapped to > KEY_BACKSLASH in hid-input.c. I am using a nordic keyboard meaning > KEY_BACKSLASH is labeled "apostrophe" and that HID key 0x32 is > reported. A US keyboard has a backslash key which should report 0x31. > > I have added some traces before the input_event call at the end of > hidinput_report_event. When pressing A key and then apostrophe, > something like this is seen (omitting all inactive keys): > > VALUE 1 CODE 30 HID 0x4 > VALUE 0 CODE 43 HID 0x31 > VALUE 0 CODE 43 HID 0x32 > Output: a > > VALUE 1 CODE 30 HID 0x4 > VALUE 0 CODE 43 HID 0x31 > VALUE 1 CODE 43 HID 0x32 > Output: ' > > VALUE 0 CODE 30 HID 0x4 > VALUE 0 CODE 43 HID 0x31 > VALUE 1 CODE 43 HID 0x32 > Output: ' > > VALUE 0 CODE 30 HID 0x4 > VALUE 0 CODE 43 HID 0x31 > VALUE 1 CODE 43 HID 0x32 > Output: ' > > VALUE 0 CODE 30 HID 0x4 > VALUE 0 CODE 43 HID 0x31 > VALUE 0 CODE 43 HID 0x32 > > So the fact that 0x31 is inactive will cause bad release events on key > 43 to be sent. > > I have made a simple patch that tracks which of the two variants is > active and ignores the other one. It works but I don't have much > knowledge on HID input so before posting it would like to know if > someone has input on how to do a cleaner fix. I am happy to help with > testing or implementation if I am able. > > Regards, > > Fredrik -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
