Here's an interesting problem which I'm not sure whether it should be fixed in PulseAudio or the driver, but I'm starting here.
I have a laptop with a HDA VIA VT1708 chip and would like auto-muting. VIA advertises auto-muting by changing the "Front Playback Switch" (see sound/pci/hda/patch_via.c:2023, via_hp_automute).
Now PulseAudio's default mixer path, "analog-output", treats "Front" as part of the volume merge chain, which in this case is incorrect, and so when the switch gets muted, PA thinks that the chain is muted and gets confused (as in: no sound output, and PA advertises to g-v-c and others that it is now muted).
It seems to me like from PA's perspective the name should have been "Speaker Playback Switch" instead, but VIA does not seem to use "Speaker" at all, and BIOS seems to have set up my caps for Speaker as "Line out", so I'm not sure if this is the right way to do it.
For reference, here's my alsa-info: http://launchpadlibrarian.net/53047763/alsa-info.txt.JUhgxH8rDZ