I installed Ubuntu 12.04 on a Dell Latitude e6530. Apparently everything works fine except one thing: volume control (sound itself is fine).
I have 3 hardware buttons (mute, - and +) that are inactive. In addition I cannot move the volume slider that appears in Unity's indicator zone: it is blocked at minimum volume. Same if I open the sound parameters: the sliders at the bottom are blocked. In addition the "Test sound" button doesn't play any sound, and in the Applications tab nothing is displayed, even if Rhythmbox is currently playing.
This isn't a sound problem: audio files play normally in Rhythmobx (I can hear the sound playing perfeclty normally with good quality), and I can even tune the volume in applications (ie Rhythmbox slider).
Weird thing is: the volume control slider is active on the login screen (not the hardware buttons). Weird thing 2: both slider and hardware buttons work in KDE.
I searched a bit on the topic, but I couldn't find anything similar. Apparently I have an Intel QM77 chipset with integrated Intel HDA 4. This chipset is certified (even though not on that specific model), so I don't understand why it is a problem.
Do you have any idea what happens and how I could solve this issue?
Thanks a lot,