[alsa-devel] maestro3 & es1988: mic range too low

[Takashi Iwai]

At Sun, 17 Aug 2008 22:07:19 +0300,
ikke wrote:
> 
> Hi,
> 
> I'm having mic problems with snd_maestro3 and es1988 allegro hw. The
> laptop is HP OmniBook Xe3. The mic is way too silent (unusable) even
> with 20db boost option on. I found this seems to have been really
> common problem, but only one came with a fix [1] to the problem,
> enabling one more bit to volume control. Could someone please help me
> apply that fix to current alsa?
> 
> I tried compiling 2.6.26.2 kernel and made the first change of the
> patch from mail [1] attachement [2]. No change. The second part of
> patch I did not find anymore from the code. There are similar parts in
> ac97_patch.c. Any hint what should be added there?

Note that "Mic Playback Volume" controls only the volume of analog
playback.  It doesn't change the recording level at all.

> The original patched code is somewhat outdated compared to modern
> one... But the reasoning for the original patch sounds reasonable. The
> mic volume is tunable, only at the very low range. I recall the laptop
> came with Win98, and there was no problem then with the sound -> not a
> HW problem. I have never got this laptop mic working with linux, so
> this is not anything that broke recently. I see there is
> check_volume_resolution function which tries to guess some of the
> register ranges, but maybe it get's it wrong with this HW.

Maybe, maybe not.  You should check rather ac97 registers in
/proc/asound/card0/codec97#0/ac97#0-0+regs.  If build with
CONFIG_SND_DEBUG=y, you can write to the register directly, too.
See Documentaiton[/sound/alsa]/Procfile.txt.


Takashi