mixer problems with SiS 7012 and CMI9761 ac97 codec

[Maxime Henrion]

	Hello all,



I'm seeing quite weird symptoms with this onboard SiS 7012 audio
controller.  The "pcm" mixer setting doesn't change the sound's volume
at all, except at 0 where it mutes the sound as expected.  The "vol"
mixer setting has absolutely no control over sound, it doesn't change
anything whether I set it to 0 or 100.

If I set the "speaker" mixer setting to 0, it outputs a very loud beep.
If I set it to 1, there is a small beep.  If I set it higher, up to 49,
the beep gets louder, and at 50 and above it doesn't output the beep
anymore.  I don't have a "ogain" channel.  Interesting, isn't it? :-)

As said in the topic, this is a SiS 7012 sound card.  It has a CMI9761
ac97 codec (id == 0x434d4982 == "CMI" 0x82).  It isn't in the list of
supported codec ids on FreeBSD.  It is however listed in ALSA's source
code, and has chipset specific support code.  I merged one of the
workaround, which is for the specific revision of the CMI9761 chipset I
have.  Unfortunately, nothing changed.

I wonder if anyone else is having problems with this chipset/ac97 codec,
or if it's working fine for others.  If someone more knowledgeable than
me in AC97 code is interested to look at the problem, I'd be glad.  I
don't know enough about this to even know where exactly the problem may
lie.

Cheers,
Maxime