[pulseaudio-discuss] PA UCM support (Volume and Jack)

[Arun Raghavan]

On Tue, 2013-08-06 at 11:00 -0700, Felipe Tonello wrote:
> Hi Arun,
> 
> On Mon, Aug 5, 2013 at 8:43 PM, Arun Raghavan
> <arun.raghavan at collabora.co.uk> wrote:
> > On Mon, 2013-08-05 at 11:43 -0700, Felipe Tonello wrote:
> >> Hi all,
> >>
> >> I'm using UCM configurations to handle multiple devices and
> >> playback/capture mixer controls. It seems that PA UCM implementation
> >> just store the PlaybackVolume PlaybackSwitch properties but doesn't
> >> make any usage of it.
> >>
> >> What I want to do is basically to be able to change hardware volume
> >> instead of just software volume. When I plug a Headphone, for
> >> instance, I want PA to change the volume of the alsa control that I
> >> specified by PlaybackVolume in the UCM file not just the sink volume.
> >>
> >> Is that possible to do? Does it require a patch or some work?
> >
> > It is possible of course, but hasn't been implemented (yet).
> 
> I will probably need this use case. I hope to send a patch in a few
> weeks to come.

Excellent!

> >
> >> Also, jack support for UCM seems to have a bug. For when using UCM
> >> support, when I start PA or change a card profile with a jack
> >> previously plugged, it doesn't recognizes that unless I unplug and
> >> plug again.
> >
> > David was looking into hooking up jack detection with UCM, so might have
> > some more useful information for you.
> 
> Actually I realized was probably a problem in my UCM configuration.
> Now it seems to be ok.
> 
> >
> >> Any comments on that as well?
> >>
> >> OBS: I'm using PA 3.0.
> >
> > You'd also mentioned the problem with modem PCMs on IRC. I think we
> > really don't have much choice here but to go with the
> > PA_SINK_ALWAYS_RUNNING flag that I'd posted earlier, coupled with adding
> > a field in the UCM to signal that this needs to be set.
> 
> I saw your patch. It was not upstreamed right? Also, how would you set
> that flag in run-time?

Correct about the former (though I'll likely rebase and resubmit it at
some point soon). As for applying it at run time, we could add a value
known to PA in the UCM 'Value' section, and then have our UCM processing
set the flag based on that.

> >
> > Yes, we would ideally like for these paths to be set up in the kernel,
> > but pragmatically, that seems to be quite unlikely to happen on the
> > Android kernels (at least it hasn't in the last year and a half).
> 
> Do you have more information about that? Because here I have control
> over the kernel, so we could implement there if needed.

Mark Brown (broonie on IRC) is probably the best person to answer this.

Cheers,
Arun