I'm running Ubuntu 12.04 on Lenovo Thinkpad E420s. Initially everything was working great, but after a while, the head phone jack stopped working. Speakers used to work just fine. So I tried out many solutions, I'll summarize below for reference:
(a) One solution asks you to modify analog-output-headphones.conf, but it didn't work for me.
(b) Another solution asks you to modify
/etc/modprobe.d/alsa-base.conf, that didn't work, but part of that would have been the solution (see the last part)
Doesn't work for me
A combination of this and 1(b) did the trick.
Basically, I uninstalled
gnome-alsamixer. I then added just the following line:
options snd-hda-intel model=generic" into /etc/modprobe.d/alsa-base.conf
Head phones started working.
But I'm facing a new problem now. Now sound is coming from both headphones and the Laptop speakers. Also, if I go to sound settings, all of the options have been disabled, including the option to select hardware and modify master volume. Even the volume buttons aren't working any more. Any suggestions how to go about fixing this?
$ lspci | grep "audio" 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)