Comment 9 for bug 376554

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jetdog (slicksterdave) wrote :

@molecule-eye , Mirco Müller

Please have a look at bug - which this is a duplicate of:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/271706

The behaviour we're seeing there with the U300 is a symptom of the volume dial being not in compliance with the PS/2 keyboard standard. Basically, after an odd number of twists, the wheel leaves the kernel input driver thinking that the "volume-down" or "volume up" is still active.

Particularily, this attachment confirms this (showkey log, which is based on /dev/console - which produces output form way before evdev even sees it):
http://launchpadlibrarian.net/27809229/mykeylog-U300.txt

This causes the kernel evdev input interface to message X endlessly that the button/state is "down" - forcing an endless volume repeat, logically started by the hardware (for incompliance with standards), which is then propagated by the kernel via evdex to X, which will finally make a repetition make it all the way to your application

I am currently working with an evdev developer for testing as well as the kernel keyboard input driver creator and maintainer to try to come up with a viable solution for systems with these incompliant hardwares that don't always return a "button release" code. (yes, granted the U300 has a wheel, but it still communicates with the PS/2 interface with the codes of a regular button ;D).

We'll be working on this via the above mentioned:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/271706

Please track the issue there.