Have you tried the solution proposed in https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/794390/comments/5? I've installed alsa-hda-dkms version 0.201111181453~oneiric1 and now auto mute works fine...
Have you tried the solution proposed in https:/ /bugs.launchpad .net/ubuntu/ +source/ alsa-driver/ +bug/794390/ comments/ 5? I've installed alsa-hda-dkms version 0.201111181453~ oneiric1 and now auto mute works fine...