Linux 6.9 pre-rc1 might have broken UCM matching for USB devices

[pinkflames]

While testing Torvalds' master branch of Linux which will become 6.9-rc1 eventually, I have stumbled upon PipeWire/WirePlumber apparently no longer applying the UCM profile for my USB connected on-board audio controller. Git bisection leads to the following commit: torvalds/linux@1601cd5 . It's possible that I'm wrong in concluding that the issue is UCM no longer applying/matching but that's my best guess looking at seemingly ACP named devices and the lack of any ucm strings in the output of pw-dump, when the regression is present.

Since this is likely a kernel regression, I'll be reporting that to the kernel bugzilla, too, but I thought alsa-ucm-conf might be interested in this change as well.

[perexg]

Could you attach output from amixer -c 0 contents (replace 0 with the correct integrated USB sound card)? Also show output from amixer -c 0 info. Thanks.

[pinkflames]

Here's the required information, when things are working correctly (regression is not present).
contents_working.txt
info_working.txt

And here's the same output with a kernel that has the issue:
contents_broken.txt
info_broken.txt

[perexg]

So this cleanup makes sense and it better identifies the purpose of the mixer element:

old naming:

numid=20,iface=MIXER,name='PCM Playback Switch'
numid=21,iface=MIXER,name='PCM Playback Volume'
numid=24,iface=MIXER,name='PCM Playback Switch',index=1
numid=25,iface=MIXER,name='PCM Playback Volume',index=1
numid=28,iface=MIXER,name='PCM Playback Switch',index=2

new naming:

numid=20,iface=MIXER,name='Speaker Playback Switch'
numid=21,iface=MIXER,name='Speaker Playback Volume'
numid=24,iface=MIXER,name='Headphone Playback Switch'
numid=25,iface=MIXER,name='Headphone Playback Volume'
numid=28,iface=MIXER,name='IEC958 In Playback Switch'

I'll try to extend ALC4080 config to handle new names so we can revert the revert :)

[pinkflames]

I'll try to keep an affected kernel image around so that I can test the fix as soon as it's ready. I can apply git commits as patches to the alsa-ucm-conf package easily, so just let me know when and what to test.

[tiwai]

The kernel isn't released yet and I'm going to revert the commit that changed the control names. We need to apply the changes a bit more carefully at the next try.
http://lore.kernel.org/r/20240316083744.28126-1-tiwai@suse.de

[perexg]

Resolved in kernel.