Pipewire doesn't support upstream google-kevin ALSA UCM config

Describe your issue

What's the expected behaviour?

The following sequence of events in the future:

PulseAudio > 16.1 is released and packaged for Alpine Linux
alsa-ucm-conf-google-gru package is dropped from pmaports
Audio devices keep working on google-kevin
PostmarketOS globally switches to PipeWire
Audio devices still keep working on google-kevin

What's the current behaviour?

Current releases of PulseAudio and PipeWire have problems with the ConflictingDevice directive as used in the upstream ALSA UCM config for google-kevin. With PulseAudio this results in some of the conflicting audio devices being unusable, with PipeWire it results in unusably choppy sound input/output. So, the alsa-ucm-conf-google-gru package splits the UCM config into two Verbs as a hack to avoid using ConflictingDevice and things work somewhat OK.

The issue is mostly fixed in PulseAudio's master branch, patches for it were picked to PipeWire and then reverted there as they found a bug. A bugfix is awaiting review as a PulseAudio MR, and it seems unlikely that the PipeWire maintainer will pick patches before they get merged into PulseAudio first.

The alsa-ucm-conf-google-gru package should be dropped when the next PulseAudio release is available in favor of the upstream UCM config. However, switching to PipeWire after that (and before the relevant patches get into PW) will regress audio support on google-kevin.

@jenneron asked me to file an issue for this as it might be a valid blocker for switching to PipeWire.

How to reproduce your issue?

Not really tested on postmarketOS, but roughly:

Remove alsa-ucm-conf-google-gru from device-google-kevin dependencies
Update pulseaudio, pipewire packages to build from git master
Build and boot USB disk with those three custom packages
Observe that audio devices works fine with pulseaudio, but not with pipewire-pulse

What device are you using?

google-kevin

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