Comment 5 for bug 950490

Yes, it is a 4-pin headset jack. I can use both the headphone and the mic simultaneously.

Adding the line
options snd-hda-intel model=laptop-dmic
to /etc/modprobe.d/alsa-base.conf solved the issue for me, at least partly. I now only have 1 microphone, but it auto-switches between the external one and the internal one depending on whether I have an external mic plugged in or not.

It would be nice to be able to use the internal mic sometimes even when the external one is connected, but it's also quite acceptable to have it this way.

So, do you still need me to try the hda-jack-retask thingy?