[pulseaudio-discuss] librem5 sound

Tanu Kaskinen tanuk at iki.fi
Sat Dec 7 17:07:24 UTC 2019

On Fri, 2019-12-06 at 08:51 -0700, Angus Ainslie wrote:
> Thanks for the latency suggestions. We added those patches to pulseaudio 
> 12.2 and it's working well.
> https://source.puri.sm/Librem5/pulseaudio/commit/a5f36231979ea0d4c414a41450d0bc28e25cb817
> Now I'm trying to map the correct alsa mixer for pulseaudio volume 
> control. I tried setting PlaybackMixerElem element but it doesn't seem 
> to be affecting the alsa mixer.
> https://github.com/pulseaudio/pulseaudio/blob/e6779ad229d5858f90f5f10c3796c9778f05c3fa/src/modules/alsa/alsa-ucm.c#L95
> purism at pureos:~$ amixer -c 1 sget Speaker
> Simple mixer control 'Speaker',0
>    Capabilities: volume pswitch
>    Playback channels: Front Left - Front Right
>    Capture channels: Front Left - Front Right
>    Limits: 0 - 127
>    Front Left: 122 [96%] [1.00dB] Playback [on]
>    Front Right: 122 [96%] [1.00dB] Playback [off]
> I tried setting it to
> PlaybackMixerElem "name='Speaker Volume'"
> and
> PlaybackMixerElem "Speaker Volume"
> and neither seemed to affect the alsa mixer volume. Am I setting the 
> wrong ucm_id or am I setting it incorrectly ?

The support for hardware volume with UCM landed only yesterday:

You can backport that, or you can disable UCM, either by removing the
UCM configuration or by passing "use_ucm=no" to module-udev-detect (or 
to module-alsa-card if you don't use module-udev-detect). If you're
lucky, the default configuration will work, but since this is embedded
hardware, it may not follow the usual Intel HDA conventions, in which
case you'll need to write some custom configuration. Some documentation
is here:



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