Public bug reported:
[Impact]
Noble's alsa-lib 1.2.11-1ubuntu0.2 cannot parse UCM control remap entries
where one virtual control maps to multiple source channels, for example:
"name='cs42l43 Speaker Digital Switch'".vindex.0 [ 0 1 ]
As a result, SoundWire systems using these UCM remaps can have broken speaker
and microphone mute fan-out: PipeWire/WirePlumber mute may not toggle all
backing ALSA controls, and the hardware mute LEDs can become inconsistent with
the actual mute state.
[Test Plan]
On affected Noble hardware, install the fixed alsa-lib packages, then regenerate
the ALSA remap cache:
$ sudo rm -f /var/lib/alsa/card0.conf.d/ctl-remap.conf
$ sudo alsactl init 0
$ systemctl --user restart pipewire wireplumber
Verify that the generated remap file contains the multi-source-channel
control:
$ sudo grep -n "cs42l43 Speaker Digital Switch" \
/var/lib/alsa/card0.conf.d/ctl-remap.conf
Verify mute behavior through PipeWire:
$ wpctl set-mute @DEFAULT_AUDIO_SINK@ 1
$ wpctl set-mute @DEFAULT_AUDIO_SOURCE@ 1
Expected result: speaker mute toggles the virtual speaker control and all AMP
speaker controls, microphone mute toggles the virtual microphone control and
both CS42L43 decimator controls, and the mute/mic-mute LEDs follow the muted
state.
[Where problems could occur]
The change is in alsa-lib's control remap plugin. A regression could affect UCM
profiles using remapped controls, causing wrong virtual-control readback, wrong
mute fan-out, or ALSA/UCM errors while parsing remap configuration.
[Other Info]
Fix by backporting upstream alsa-lib commit:
6855cb838d0a69183e1db6429bc9c14265b68240
control: remap - add possibility to remap multiple source channels
https://github.com/alsa-project/alsa-
lib/commit/6855cb838d0a69183e1db6429bc9c14265b68240
This fix is already included upstream in alsa-lib 1.2.14 and later. Noble stays
on alsa-lib 1.2.11, so it needs this targeted backport.
** Affects: alsa-lib (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2159614
Title:
[SRU] alsa-lib: support control remap entries with multiple source
channels
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