[alsa-devel] Mic Boost control problem with snd-hda-intel codec AL662 rev 1

Takashi Iwai tiwai at suse.de
Tue Jan 12 12:43:13 CET 2010

At Wed, 6 Jan 2010 16:43:38 +0100,
Anisse Astier wrote:
> Hi,
> The Mic Boost control on a laptop seems to behave incorrectly. The
> control has the flag "volume" instead of "cvolume", causing it to appear
> in both the "Playback" and "Capture" tabs of alsamixer.
> This wouldn't be a problem if it would just work in the Capture tab: it
> doesn't.
> When I modify it in Capture, it doesn't retain its value: it's gone after
> i close alsamixer. But if i modify it in "Playback" it will retain its
> value and the value will be mirrored by the Mic Boost in Capture (both
> Mic Boost seem to reflect the same control, except one is RO, the other
> is RW).
> It's a minor a annoyance, but I'd like to fix it and have "Mic Boost"
> appear only as a Capture control and retaining its value. Maybe I should
> create a new mixer configuration for this hardware in patch_realtek.c, but
> I don't know where to start. Bios autoprobing works for everything but
> just what I mentioned.

Well, Mic Boost is applied to both playback and capture in case you
have analog loopback.  So, it's not entirely wrong.

The problem is rather the inconsistent behavior in alsamixer.
I guess it's a bug of old alsa-lib.  Try to upgrade the alsa-lib and
alsa-utils first.


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