[alsa-devel] pcm512x driver: Mixer control naming issue

[Takashi Iwai]

At Sun, 15 Mar 2015 22:28:01 +0000,
Howard Mitchell wrote:
> 
> On 13/03/15 18:27, Mark Brown wrote:
> > On Fri, Mar 13, 2015 at 12:41:05PM +0000, Howard Mitchell wrote:
> >
> >> Boost Volume) provides a boost of +0.8dB. The hardware reset value of both
> >> of these gain controls is 0dB, however, in the Raspbian distribution
> >> 'Playback Volume' is being defaulted to -6dB.
> >>   * Either change the names of these controls to something that's not
> >>     affected by the alsa restore mechanism,
> > You say "these controls" but it seems like only "Playback Volume" has
> > a problem?  My first suggestion would be to define "Analog" or
> > "Analogue" as a prefix in ControlNames and then use that, that would
> > avoid confusing applications while still fittig in with the naming
> > convention.
> Yes you are correct that it's only "Playback Volume" that is causing a 
> problem. However, I included "Playback Boost Volume" as it also provides 
> a selection of analogue gain so I think it should be treated similarly 
> for consistency.

Did you read Documentation/sound/alsa/ControlNames.txt?
It shows why "Playback Volume" is taken in that way while "Playback
Boost Volume" not.  Namely, the latter implies a volume control named
"Playback Boost" which is applied generically -- i.e. the direction is
unknown or applied to both playback and capture.


Takashi