Comment 3 for bug 1316156

I am also affected by this bug, using 14.04 LTS.

Hardware:
Asus Pro52H Notebook
Sound-Chip is as described above: Intel HDA, AD1986A NM10/ICH7

The symptom is also as described above:
In the alsamixer the port is continually switching between Speakers and Headphones.
In result on the desktop you can see a constantly "blinking" volume display.

This happens just with the basic installation (auto detection), so the default installation already leads to the bug.

In can confirm that the bug is related to the auto mute feature, it only happens when auto mute is enabled. On the other hand having it disabled, I got no sound at all (though at least no blinking volume display on the screen).

Currently I am using this setting in alsa-base.conf:

options snd-hda-intel model=laptop-eapd position_fix=1

With this at least I got the headphones working and the blinking volume display does not appear any more.
As said, speaker not working, already the speaker port is said to be "not available" in the sound control.

Using that manual option last year I already had a fully working sound in an earlier release, I think it was 13.04, though I am not 100% sure.