I upgraded to 12.1 and my sound stopped working. I found out there’s a bug in kernel 3.1.0 for ALC861. You can check if you have it with:
aplay -l
Ouput:
**** List of PLAYBACK Hardware Devices ****
card 0: SB [HDA ATI SB], device 0: ALC861 Analog [ALC861 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
There’s a fix for it in kernel 3.1.1. I installed the kernel from here and got my sound back: