Comment 4 for bug 595482

I have the same laptop (LG P1 Express) and the same problem. I am also using the "model=lg" quirk to have it working.
Everything works as expected when I use the "model=lg" option, except one thing: I have to "reselect" the mic (click on other mic, or in Line-In, and then on the Mic again) in the mixer on every reboot in order to have it working. If I don't do this, the mic doesn't work.