Dumping what I know, hoping it will help. Additions were made to sound/pci/hda/patch_hdmi.c in 3.8.0-18, and removing them solves the problem. As I can see, they are based on 3.9-rc*, but it seems that upstream some other additions were made. I added a patch to better illustrate what's causing the problem, it's not meant to be a solution.
** Patch added: "hdmi.patch" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1169761/+attachment/3651287/+files/hdmi.patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1169761 Title: 3.8.0-18 Kernel causes HDMI Audio to stop working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1169761/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs