[ltp] Re: How are hotkey and ACPI events handled on newer Thinkpads (2010+) with 3.x kernels?

Chow Loong Jin linux-thinkpad@linux-thinkpad.org
Tue, 22 Jan 2013 01:00:37 +0800

On 21/01/2013 17:09, Jonas Camillus Jeppesen wrote:
> xev registers all fn+fx events and fn+end/home both with and without gnome
> running. xev does not register the dedicated volume up/down and mute keys.
> A thing that puzzles me is that the brightness up/down keys (fn+end/home) works
> both with and without gnome whereas other keys (toggle tuochpad for example)
> does not (they are captured by xev but nothing happens). What makes the
> brightness keys special and what handles those keys compared to what handles all
> the other keys? Whatever handles the brightness keys seem to be running
> independent of gnome whereas what ever handles the other keys is somehow
> dependent on gnome. Any ideas?

I think you'll find that the brightness keys are very special, even on the
firmware level. For example, on the Thinkpad E220S, the F7 and F8 keys send out
duplicate keypresses. Hardware keydown -> software keydown + keyup; hardware
keyup -> software keydown + keyup. Yeah, it's stupid like that.

Incidentally, F7 and F8 are the keys responsible for brightness control on that
Thinkpad (when Fn isn't pressed).

Kind regards,
Loong Jin