Comment 90 for bug 141445

@Daniel Chen
Thanks, you are right. I removed the model=sony-assamd form snd-hda-intel modprobe options.

@ slayerdme
Thank you, you gave me the idea and I used amixer like this:
amixer sset 'Input Source' 'Int DMic'

this command will change the input source to Internal microphone and I put it in autostart as a .desktop file to run after login. this fixed the problem because running it before gnome login (e.g in rc.local) is cancelled at login.

if someone needs more info about how to run a command at gnome autostart, just look at
/usr/share/gnome/autostart/libcanberra-login-sound.desktop
and create a file like that in the same directory for your own command.

Cheers,
Rex