[alsa-devel] [PATCH 2/5] ALSA: hda - More generic auto-mic switching for Realtek codecs

[Raymond Yau]

>
> Instead of limiting the automatic input-source selection only to the
> mics (internal, external and dock mics), allow it for generic inputs,
> e.g. switching between the rear line-in and the front mic.

the problem of addng line in jack to auto mic is line in does not has any
boost (gain) but most mic have a boost control

the other problem is those acer aspire 8930g notebook has internal 5.1
speakers and three jacks which can support external 5.1 speakers

it seem the the channel mode control limit the max channels to 2 when there
is internal 5.1 speaker

when channel mode is 6ch the mic jack is retasked as output and cannot be
used

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/943386