Comment 56 for bug 266927

What does seem to work for me (at least, my sound has now been working for the last few days) is the fix mentioned in comment #45, adapted to my computer (a Mac Mini).

Therefore, the real fix seems to be to add a quirk to the module for each machine that needs one. In my case:

options snd-hda-intel model=intel-mac-auto position_fix=2 probe_mask=1

in /etc/modprobe.d/alsa-base.conf

I shall report the need for a quirk upstream.