In reply to @sporesirius:matrix.org
Yeah, there is a commit. It's a one-line fix, I tried that first, but unfortunately it didn't work, so I tried the method described above.

doing a nixos config like the below should patch in the fix and then graft it into your system. it, uh, doesn't work in pure eval (e.g. flakes) so you'll need to add --impure or something if you use flakes (it also needs IFD, but unless you manually disabled that, it should be enabled):

system.replaceRuntimeDependencies = [
  ({
    original = pkgs.alsa-ucm-conf;
    replacement = pkgs.alsa-ucm-conf.overrideAttrs (oldAttrs: {
      patches = (oldAttrs.patches or []) ++ [
        (fetchpatch {
          name = "alsa-ucm-conf-splitpcm-device-argument-fix.patch";
          url = "https://github.com/alsa-project/alsa-ucm-conf/commit/b68aa52acdd2763fedad5eec0f435fbf43e5ccc6.patch";
          hash = "sha256-8WE4+uhi4W7cCSZYmL7uFpcHJ9muX09UkGXyZIpEd9I=";
        })
      ];
    });
  })
];

and you should be able to PR a diff like this to nixpkgs staging branch:

diff --git a/pkgs/by-name/al/alsa-ucm-conf/package.nix b/pkgs/by-name/al/alsa-ucm-conf/package.nix
index b7203a737638..c77b2024dc4e 100644
--- a/pkgs/by-name/al/alsa-ucm-conf/package.nix
+++ b/pkgs/by-name/al/alsa-ucm-conf/package.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl }:
+{ lib, stdenv, fetchurl, fetchpatch }:
 
 stdenv.mkDerivation rec {
   pname = "alsa-ucm-conf";
@@ -9,6 +9,14 @@ stdenv.mkDerivation rec {
     hash = "sha256-nCHj8B/wC6p1jfF+hnzTbiTrtBpr7ElzfpkQXhbyrpc=";
   };
 
+  patches = [
+    (fetchpatch {
+      name = "alsa-ucm-conf-splitpcm-device-argument-fix.patch";
+      url = "https://github.com/alsa-project/alsa-ucm-conf/commit/b68aa52acdd2763fedad5eec0f435fbf43e5ccc6.patch";
+      hash = "sha256-8WE4+uhi4W7cCSZYmL7uFpcHJ9muX09UkGXyZIpEd9I=";
+    })
+  ];
+
   dontBuild = true;
 
   installPhase = ''

In reply to @sporesirius:matrix.org
Yeah, there is a commit. It's a one-line fix, I tried that first, but unfortunately it didn't work, so I tried the method described above.

doing a nixos config like the below should patch in the fix and then graft it into your system. it, uh, doesn't work in pure eval (e.g. flakes) so you'll need to add --impure or something if you use flakes (it also needs IFD, but unless you manually disabled that, it should be enabled):

system.replaceRuntimeDependencies = [
  ({
    original = pkgs.alsa-ucm-conf;
    replacement = pkgs.alsa-ucm-conf.overrideAttrs (oldAttrs: {
      patches = (oldAttrs.patches or []) ++ [
        (fetchpatch {
          name = "alsa-ucm-conf-splitpcm-device-argument-fix.patch";
          url = "https://github.com/alsa-project/alsa-ucm-conf/commit/b68aa52acdd2763fedad5eec0f435fbf43e5ccc6.patch";
          hash = "sha256-8WE4+uhi4W7cCSZYmL7uFpcHJ9muX09UkGXyZIpEd9I=";
        })
      ];
    });
  })
];

In reply to @lily:lily.flowers

doing a nixos config like the below should patch in the fix and then graft it into your system. it, uh, doesn't work in pure eval (e.g. flakes) so you'll need to add --impure or something if you use flakes (it also needs IFD, but unless you manually disabled that, it should be enabled):

system.replaceRuntimeDependencies = [
  ({
    original = pkgs.alsa-ucm-conf;
    replacement = pkgs.alsa-ucm-conf.overrideAttrs (oldAttrs: {
      patches = (oldAttrs.patches or []) ++ [
        (fetchpatch {
          name = "alsa-ucm-conf-splitpcm-device-argument-fix.patch";
          url = "https://github.com/alsa-project/alsa-ucm-conf/commit/b68aa52acdd2763fedad5eec0f435fbf43e5ccc6.patch";
          hash = "sha256-8WE4+uhi4W7cCSZYmL7uFpcHJ9muX09UkGXyZIpEd9I=";
        })
      ];
    });
  })
];