gamescope: Add QAM synthesis patch

This patch aims to make the QAM accessible from in-game via a well-known
keyboard binding. The binding chosen is F22, since it shouldn't clash
with any usual keyboard keys.

Not part of this change set: adding support for the QAM to a
non-steamdeck device.

overlay.nix

@@ -23,7 +23,7 @@ rec {
 
   gamescope = import ./pkgs/gamescope {
     gamescope' = prev.gamescope;
-    inherit (final) fetchFromGitHub;
+    inherit (final) fetchFromGitHub fetchpatch;
   };
   gamescope-wsi = gamescope.override {
     enableExecutable = false;

pkgs/gamescope/default.nix

@@ -1,9 +1,11 @@
 { gamescope'
+, fetchpatch
 , fetchFromGitHub
 }:
 
 # NOTE: vendoring gamescope for the time being since we want to match the
 #       version shipped by the vendor, ensuring feature level is equivalent.
+#       We're also patching-in features.
 
 gamescope'.overrideAttrs(old: rec {
   version = "3.15.14";
@@ -15,4 +17,12 @@ gamescope'.overrideAttrs(old: rec {
     fetchSubmodules = true;
     hash = "sha256-LVwwkISokjSXEYd/SFRtCDDY6P2sr6pQp8Xb8BsrXAw=";
   };
+
+  patches = old.patches ++ [
+    # wlserver: Sythesize QAM combo on F22
+    (fetchpatch {
+      url = "https://github.com/ValveSoftware/gamescope/commit/3df5a1bc977d36b68e15371b25dadc0380ffc9e0.patch";
+      hash = "sha256-BbwAxJYPulOVB7m17R9yskwOePprSwoqKJ1V7dEASJI=";
+    })
+  ];
 })