Soft buttons and keyboard shortcuts sometimes don't work on HP EliteBook 6930p

[Exeleration-G]

On my HP EliteBook 6930p, there are some soft buttons, the most important being Mute, Volume Up, Volume Down.

Sometimes, these soft buttons don't work. Interesting: in those cases, normal keyboard shortcuts (for example: Ctrl + Alt + T for opening a terminal) also don't work. I have to reboot my system, and then, they usually work again.

In those cases, the buttons themselves do work: the mute button indicator on the keyboard will switch from blue to red and the volume buttons will do a 'bouncing' animation to confirm that you've pressed those buttons. Additionally, I do believe that in those cases the buttons are interpreted somehow by the system, because for instance, when running

xev | grep -A2 --line-buffered '^KeyRelease' | sed -n '/keycode /s/^.*keycode \([0-9]*\).* (.*, \(.*\)).*$/\1 \2/p'

(source: https://wiki.archlinux.org/index.php/Extra_keyboard_keys#In_Xorg)

I get the following output when pressing those buttons:

36 Return
122 XF86AudioLowerVolume
123 XF86AudioRaiseVolume

So there must be something else going on. I just don't know what to do from here. Any help here is appreciated.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.16.0-33-generic 3.16.0-33.44~14.04.1
ProcVersionSignature: Ubuntu 3.16.0-33.44~14.04.1-generic 3.16.7-ckt7
Uname: Linux 3.16.0-33-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.8
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Apr 6 20:44:12 2015
InstallationDate: Installed on 2015-03-01 (36 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
SourcePackage: linux-lts-utopic
UpgradeStatus: No upgrade log present (probably fresh install)

[penalvch (penalvch)]

Exeleration-G, thank you for reporting this and helping make Ubuntu better. Could you please execute the following command, as it will automatically gather debugging information, in a terminal:
apport-collect 1440846

[Exeleration-G (exeleration-g)]

Hi Christopher, thank you for looking into this. I'm running Ubuntu MATE 15.04 at the moment, and the problem doesn't happen in that distro.

Maybe somebody else will be able to pick up this bug from where I left off?

[penalvch (penalvch)]

Exeleration-G, this bug report is being closed due to your last comment https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1440846/comments/3 regarding you are not using Ubuntu. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status. Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.