My keyboard doesn't have a Linux driver, can someone tell me what these error messages mean?

Question

This question may be better asked on unix.stackexchange.com, but I'm asking it here because I'm quite sure someone will have an answer.

My keybaord doesn't have a driver for Linux, and I'm thinking about trying to write one as a way to learn C. I have a book but a good project is also helpful. I don't really know how to go about doing that, but thats a question for another place and time. The question I have now is what do the following error messages mean?

I get 54 of these on boot, each with a different leading number in the brackets.

[ 1.543402] hid-generic 0003:05C7:2012.0004: unknown main item tag 0x0

and then I get 1 of these:

[ 1.546827] hid-generic 0003:05C7:2012.0004: unbalanced collection at end of report description

and 1 of these :

[ 1.547479] hid-generic: probe of 0003:05C7:2012.0004 failed with error -22

Can someone tell me what these mean? I know for a fact it's my keyboard. The messages go away when I unplug it.

Answer 1

I apologize for spoiling your fun, but it does not sound like a good project. For one thing, there is this Launchpad bug report which sounds very similar to yours indeed. Second, there is a possible solution on the ever helpful Arch Linux wiki: it is recommended that you enable EHCI Hand-off in your BIOS settings.

If it is indeed a bug, or a misconfiguration of the BIOS settings, it is hardly a matter to be solved by writing a good driver. My personal inclination is that it is a matter of BIOS setting (will you let me know?) because this German fellow reports using exactly your generic keyboard without a hitch in 2006. He displays the output of

cat /proc/bus/input/devices
.......
I: Bus=0003 Vendor=05c7 Product=2012 Version=0001
N: Name="Generic USB K/B"

which is exactly your keyboard as reported by

[    1.543402] hid-generic 0003:05C7:2012.0004: unknown main item tag 0x0

As for the meaning of the error messages, I can help you only partially: hid-generic is a driver for HID-compatible peripherals. HID (=Human Interface Device) is a protocol for the specification of input/output devices assuring compatibility of components across different computers. You can find a good intro to HID here.

You were searching for an (advanced!) C project: you may then hunt down the error messages you find in the code of the hid-generic driver I referenced above. I am too lazy to do it myself.