[alsa-devel] Muting of the "Front" mixer control

Takashi Iwai tiwai at suse.de
Thu Aug 5 12:37:11 CEST 2010

At Wed, 04 Aug 2010 16:42:50 +0200,
David Henningsson wrote:
> Here's an interesting problem which I'm not sure whether it should be
> fixed in PulseAudio or the driver, but I'm starting here.
> I have a laptop with a HDA VIA VT1708 chip and would like auto-muting.
> VIA advertises auto-muting by changing the "Front Playback Switch" (see
> sound/pci/hda/patch_via.c:2023, via_hp_automute).
> Now PulseAudio's default mixer path, "analog-output", treats "Front" as
> part of the volume merge chain, which in this case is incorrect, and so
> when the switch gets muted, PA thinks that the chain is muted and gets
> confused (as in: no sound output, and PA advertises to g-v-c and others
> that it is now muted).
> It seems to me like from PA's perspective the name should have been
> "Speaker Playback Switch" instead, but VIA does not seem to use
> "Speaker" at all, and BIOS seems to have set up my caps for Speaker as
> "Line out", so I'm not sure if this is the right way to do it.
> For reference, here's my alsa-info:
> http://launchpadlibrarian.net/53047763/alsa-info.txt.JUhgxH8rDZ

The current implementation of VIA HD-audio codecs are somehow messy
and I hope someone will really clean up the stuff there to follow
other standards.


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