alsa-ucm-conf: patch custom PinePhone conf into the upstream package rather than shipping *only* the PinePhone configs

this is more to faciliate a goal of eventually not shipping any custom audio profiles

i.e. stay close to how upstream does things until we reach that goal

-mnote that this doesn't actually override the alsa-ucm-conf nix package (yet).

doing so is costly

hosts/by-name/moby/default.nix

@@ -77,14 +77,11 @@
   # enable rotation sensor
   hardware.sensor.iio.enable = true;
 
-  # from https://gitlab.manjaro.org/manjaro-arm/packages/community/phosh/alsa-ucm-pinephone
-  # mobile-nixos does this same thing, with *slightly different settings*.
-  # i trust manjaro more because the guy maintaining that is actively trying to upstream into alsa-ucm-conf.
-  # an alternative may be to build a custom alsa with the PinePhone config patch applied:
-  # - <https://github.com/alsa-project/alsa-ucm-conf/pull/134>
-  # that would make this be not device-specific
-  environment.variables.ALSA_CONFIG_UCM2 = "${./ucm2}";
-  systemd.services.pulseaudio.environment.ALSA_CONFIG_UCM2 = "${./ucm2}";
+  # inject specialized alsa configs via the environment.
+  # specifically, this gets the pinephone headphones & internal earpiece working.
+  # see pkgs/patched/alsa-ucm-conf for more info
+  environment.variables.ALSA_CONFIG_UCM2 = "${pkgs.alsa-ucm-conf-sane}/share/alsa/ucm2";
+  systemd.services.pulseaudio.environment.ALSA_CONFIG_UCM2 = "${pkgs.alsa-ucm-conf-sane}/share/alsa/ucm2";
 
   hardware.opengl.driSupport = true;
 }

nixpatches/2023-05-31-toplevel-alsa.patch

@@ -0,0 +1,14 @@
+diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
+index d188ecdda55..69174ba7dc7 100644
+--- a/pkgs/top-level/all-packages.nix
++++ b/pkgs/top-level/all-packages.nix
+@@ -26607,7 +26607,8 @@ with pkgs;
+ 
+   tinyalsa = callPackage ../os-specific/linux/tinyalsa { };
+ 
+-  inherit (callPackage ../os-specific/linux/alsa-project { })
++  alsa-project = callPackage ../os-specific/linux/alsa-project { };
++  inherit (alsa-project)
+     alsa-firmware
+     alsa-lib
+     alsa-oss

nixpatches/list.nix

@@ -150,6 +150,9 @@ in [
     hash = "sha256-9XKPNg7TewicfbMgiASpYysTs5aduIVP+4onz+noc/0=";
   })
 
+  # make alsa-project members overridable
+  ./2023-05-31-toplevel-alsa.patch
+
   # for raspberry pi: allow building u-boot for rpi 4{,00}
   # TODO: remove after upstreamed: https://github.com/NixOS/nixpkgs/pull/176018
   #   (it's a dupe of https://github.com/NixOS/nixpkgs/pull/112677 )

pkgs/default.nix

@@ -19,6 +19,7 @@ let
     sane-lib = import ../modules/lib final';
 
     ### ADDITIONAL PACKAGES
+    alsa-ucm-conf-sane = callPackage ./patched/alsa-ucm-conf { inherit (unpatched) alsa-ucm-conf; };
     bonsai = unpatched.bonsai or (callPackage ./additional/bonsai { });
     bootpart-uefi-x86_64 = callPackage ./additional/bootpart-uefi-x86_64 { };
     browserpass-extension = callPackage ./additional/browserpass-extension { };
@@ -63,6 +64,13 @@ let
     # - pkgs.callPackage draws from the _final_ package set.
     # - unpatched.XYZ draws (selectively) from the _unpatched_ package set.
     # see <overlays/pkgs.nix>
+
+    # XXX patching this is... really costly.
+    # prefer to set ALSA_CONFIG_UCM2 = "${pkgs.alsa-ucm-conf-sane}/share/alsa/ucm2" if possible instead.
+    # alsa-project = unpatched.alsa-project.overrideScope' (sself: ssuper: {
+    #   alsa-ucm-conf = sself.callPackage ./patched/alsa-ucm-conf { inherit (ssuper) alsa-ucm-conf; };
+    # });
+
     browserpass = callPackage ./patched/browserpass { inherit (unpatched) browserpass; };
 
     # mozilla keeps nerfing itself and removing configuration options

pkgs/patched/alsa-ucm-conf/default.nix

@@ -0,0 +1,24 @@
+{ alsa-ucm-conf }:
+alsa-ucm-conf.overrideAttrs (upstream: {
+  # upstream alsa ships with PinePhone audio configs, but they don't actually produce sound.
+  # see: <https://github.com/alsa-project/alsa-ucm-conf/pull/134>
+  # these audio files come from some revision of:
+  # - <https://gitlab.manjaro.org/manjaro-arm/packages/community/phosh/alsa-ucm-pinephone>
+  #
+  # alternative to patching is to plumb `ALSA_CONFIG_UCM2 = "${./ucm2}"` environment variable into the relevant places
+  # e.g. `systemd.services.pulseaudio.environment`.
+  # that leaves more opportunity for gaps (i.e. missing a service),
+  # on the other hand thie method causes about 500 packages to be rebuilt
+  #
+  # note that with these files, the following audio device support:
+  # - headphones work.
+  # - "internal earpiece" works.
+  # - "internal speaker" doesn't work.
+  # - "analog output" doesn't work.
+  postPatch = upstream.postPatch or "" + ''
+    cp ${./ucm2/PinePhone}/* ucm2/Allwinner/A64/PinePhone/
+    # fix the self-contained ucm files i source from to have correct path within the alsa-ucm-conf source tree
+    sed -i 's:"HiFi.conf":"/Allwinner/A64/PinePhone/HiFi.conf":' ucm2/Allwinner/A64/PinePhone/PinePhone.conf
+    sed -i 's:"VoiceCall.conf":"/Allwinner/A64/PinePhone/VoiceCall.conf":' ucm2/Allwinner/A64/PinePhone/PinePhone.conf
+  '';
+})