Use UCM profiles for HDMI-only cards

Use UCM profiles for HDMI-only cards

[GitHub pull_request - opened]

alsa-project/alsa-ucm-conf pull request #859 was opened from felagund:

Some laptops have several outputs capable of driving several different monitors, which can in turn have their own audio capabilities. In my case, I have two monitors, each capable of audio output and sometimes I connect my AVR that is hooked to a 5.1 audio sytem.

Currently that is exposed as one device with several different profiles. That means only one can be selected at a time and it is not possible to assign different outputs to different audio streams, which the hardware is perfectly capable of.

This corrects this by applying UCM to such cards by default (previously they were ignored).

Second commit provides infrastructure for selected cards to opt out of it. I am not sure which one they are and how common they are. Until they are identified, I can also drop the second commit.

I originally tried to solve this at Pipewire level, but its maintainer thinks it is better done here: https://gitlab.freedesktop.org/pipewire/pipewire/-/merge_requests/2990#note_3652941 and indeed this is much less code for the same effect. That is also where the worry about some cards not supporting this comes from. I personally have no idea how common that is.

What I am trying to achieve is to have this (KDE sound applet):

<img width="610" height="474" alt="Screenshot_20260921_141249" src="https://github.com/user-attachments/assets/5825cd08-59a5-4539-8b53-2547343a224a" />

instead of this:

<img width="610" height="474" alt="Screenshot_20260921_142955" src="https://github.com/user-attachments/assets/50c6a075-4027-4c1b-9401-c016d61838af" />

By the way the "Play HiFi quality Music" comment field bubbles up to the profile name, which is a bit awkward. Could be changed to something like "HDMI/DP Output" maybe.

Request URL   : https://github.com/alsa-project/alsa-ucm-conf/pull/859
Patch URL     : https://github.com/alsa-project/alsa-ucm-conf/pull/859.patch
Repository URL: https://github.com/alsa-project/alsa-ucm-conf