Steinberg UR44C (0499:1730) incorrectly matched to UR44 UCM profile (PlaybackChannels mismatch)

alsa-project/alsa-ucm-conf issue #799 was edited from abentley:

Note: Google AGY wrote this, but I have manually verified all claims.

The Steinberg UR44C (USB ID  0499:1730 ) is currently matched to the  Steinberg/UR44  UCM profile in  ucm2/USB-Audio/USB-Audio.conf  via the following rule:
                                                                                                                                                                     
    If.steinberg-ur44 {
        Condition {
            Type RegexMatch
            String "${CardComponents}"                                                                                                                                
            Regex "USB0499:17((00)|(30)|(04))"
        }
        True.Define.ProfileName "Steinberg/UR44"
    }

However, the UR44 UCM profile defines  PlaybackChannels=4  (since the original UR44 only has 4 output channels).
The UR44C hardware actually exposes 6 playback channels (as confirmed by  /proc/asound/cardX/stream0 ):

    Playback:
      Interface 1
        Altset 1
        Format: S32_LE
        Channels: 6

This mismatch causes WirePlumber/PipeWire to fail to load the UCM profile with the following validation error:

    spa.alsa: Error in ALSA UCM profile for _ucm0003.hw:UR44C,0 (HiFi: Line2: sink): PlaybackChannels=4 < avail 6
    spa.alsa: Errors in ALSA UCM profile for card Steinberg UR44C

Suggested Fix:
Exclude the UR44C product ID ( 1730 ) from the  steinberg-ur44  regex condition so it falls back to standard ALSA Card Profiles (ACP) instead of attempting to load  the incompatible UR44 UCM profile.

Issue URL     : https://github.com/alsa-project/alsa-ucm-conf/issues/799
Repository URL: https://github.com/alsa-project/alsa-ucm-conf