Dell Integrated Microphone on Debian Testing
I installed Debian Testing lately on my Dell Inspiron 1545 and my integrated microphone didn't work.
To make it work, add the following line at the end of /etc/modprobe.d/alsa-base.conf:
options snd-hda-intel model=dell-m6
then, # alsa force-reload
and finally, there might be a little bit of fiddling using alsamixer. In a terminal, type alsamixer, press [TAB] to get to the input screen. I had to switch to Internal 1 to have it work: