[alsa-devel] [ALSA] HDA: no sound in headphone-out caused by commit f889fa91ad47e (2.6.25-rc1 regression)

[Takashi Iwai]

At Tue, 12 Feb 2008 19:24:35 +0100,
Matej Laitl wrote:
> 
> > > So there are now 3 vol controls that affect both speakers and headphones:
> > > * Master (which appeared somewhere between 2.6.24 and .25-rc1), when set
> > > to zero, the sound is still audible in speakers and headphones
> >
> > This must be the behavior of the codec chip...  Did "Front" volume 0
> > mute in the earlier version?  If not, it actually doesn't mute with
> > the lowest volume.  Use the master switch to mute.
> >
> > Anyway, attach the alsa-info.sh output at the moment Master volume is
> > zero.
> 
> No, setting Master and/or Front channel to 0% did not mute audio in any 
> version I used.
> 
> I'm now listening to music with Master=0% and Front=0%, the sound is at well 
> audible volume. Pastebin for this configuraion is here:
> http://pastebin.ca/901459

Thanks.  The amp values in the codec are indeed set to zero, so this
is the minimal volume level, but the codec chip apparently doesn't
mute the sound.

> However I don't consider it a problem, it's mutable by PCM and HP/Speaker 
> switches. Funny thing is that resulting volume of those 3 setting is equal:
> * Master=0, Front=0
> * Master=100%, Front=0
> * Master=0, Front=100%
> But when both set to let's say 50, changing one of these audibly affects 
> resulting volume.

It's because the master volume is implemented virtually to bind
several mixer volumes together.  The codec chip has no corresponding
functionality.


Takashi