Comment 88 for bug 153963

I have a Vostro 1400 and ran through all the steps listed in this thread, and have had no luck getting the digital mic to work:

First,I placed "options snd-hda-intel model=dell-3stack" into /etc/modprobe.d/alsa-base

Then I followed the steps that Pawel proposed:

1) added gutsy-proposed to my sources.list -- done
2) ran apt-get update -- done
3) installed linux-backports-modules -- done
4) restarted the laptop to reload the kernel and modules -- done
5) ran alsamixer and set the following settings:
   Section: [All]
     Digital Input Source: Digital -- PROBLEM!

In alsamixer, there is a "Digital" slider, but I am unable to select "Digital" (or anything for that matter) for the "Digital Input Source."

After that try failed, I followed what Sympy did, building ALSA 1.0.16 from source. It built and installed no problem, and upon reboot the sound worked fine. However, the mic was in the same situation as before ( a "digital" slider but no option to set "digital" or "digital mic" as the Digital Input Source.

Sympy, I'd be very curious to hear how you got the mic to work, or if anyone else has any ideas I would be more than happy to try them.