feat(14900k): add MediaTek MT7927 WiFi and Bluetooth support

Add a private module to enable MediaTek MT7927 (Filogic 380) support.
This includes a firmware path fix for Bluetooth and a systemd service
to force-load patched out-of-tree kernel modules, bypassing in-tree
drivers that lack support for this hardware on nixos-unstable.

flake.nix

@@ -203,6 +203,9 @@
     hermes = {
       url = "github:NousResearch/hermes-agent";
     };
+    mt7927 = {
+      url = "github:cmspam/mt7927-nixos";
+    };
   };
 
   outputs = inputs:

modules/hosts/14900k/_private/mediatek-mt7927.nix

@@ -0,0 +1,107 @@
+{ pkgs, inputs, ... }:
+# All MediaTek MT7927 / MT6639 (Filogic 380) WiFi 7 + Bluetooth support for this
+# host in one place: the upstream flake module, the hardware enablement, and the
+# workarounds needed to actually make it function on nixos-unstable.
+#
+# Workaround background: on current nixos-unstable, `boot.extraModulePackages`
+# modules placed in `extra/` are NOT indexed by `depmod` (modules.dep /
+# modules.alias contain zero `extra/` entries). As a result `modprobe`/udev
+# resolve mt7925e / btusb to the stock in-tree drivers, which do not support the
+# MediaTek MT7927 (14c3:7927). We therefore force the patched out-of-tree modules
+# to load by explicit path, blacklist the in-tree collisions so udev cannot bind
+# them first, and fix the BT firmware path the driver expects.
+let
+  # The upstream mt7927 flake installs the BT firmware under
+  # `mediatek/mt6639/`, but the patched btmtk driver requests it from
+  # `mediatek/mt7927/`. Provide it at the expected path.
+  mt7927BtFirmwareFix = pkgs.runCommand "mt7927-bt-firmware-fix" { } ''
+    src="${inputs.mt7927.packages.${pkgs.system}.firmware}/lib/firmware/mediatek/mt6639/BT_RAM_CODE_MT6639_2_1_hdr.bin"
+    install -Dm644 "$src" \
+      "$out/lib/firmware/mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin"
+  '';
+in
+{
+  imports = [
+    inputs.mt7927.nixosModules.default
+  ];
+
+  hardware.mediatek-mt7927 = {
+    enable = true;
+    enableWifi = true;
+    enableBluetooth = true;
+    disableAspm = true; # Highly recommended to fix upload speeds
+  };
+
+  hardware.firmware = [ mt7927BtFirmwareFix ];
+
+  boot.blacklistedKernelModules = [
+    # Whole mt76 stack (patched extra/ copy replaces it entirely).
+    "mt76"
+    "mt76_connac_lib"
+    "mt792x_lib"
+    "mt7921_common"
+    "mt7921e"
+    "mt7925_common"
+    "mt7925e"
+    # Patched bluetooth.
+    "btusb"
+    "btmtk"
+  ];
+
+  systemd.services.mt7927-force = {
+    description = "Force-load patched MediaTek MT7927 (Filogic 380) kernel modules";
+    wantedBy = [ "multi-user.target" ];
+    before = [ "network.target" "NetworkManager.service" ];
+    path = [ pkgs.kmod ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    script = ''
+      KVER="$(uname -r)"
+      EXTRA="/run/booted-system/kernel-modules/lib/modules/$KVER/extra"
+
+      # Load in-tree core dependencies (these ARE indexed, so modprobe works).
+      modprobe mac80211 cfg80211 rfkill led-class bluetooth || true
+
+      # Defensive: drop any in-tree mt76 modules that may have been pulled in
+      # (e.g. via boot.kernelModules) so the patched copies can bind instead.
+      rmmod mt7925e mt7921e mt7925_common mt7921_common mt792x_lib mt76_connac_lib mt76 2>/dev/null || true
+
+      insmod_x() {
+        local mod="$1"
+        local name
+        name="''${mod##*/}"; name="''${name%.ko}"
+        if lsmod | grep -q "^$name "; then
+          echo "mt7927-force: $name already loaded, skipping"
+        else
+          echo "mt7927-force: insmod $mod"
+          insmod "$mod" || echo "mt7927-force: FAILED to insmod $mod"
+        fi
+      }
+
+      # Patched mt76 stack (full replacement, dependency order).
+      insmod_x "$EXTRA/mt76/mt76.ko"
+      insmod_x "$EXTRA/mt76/mt76-connac-lib.ko"
+      insmod_x "$EXTRA/mt76/mt792x-lib.ko"
+      insmod_x "$EXTRA/mt76/mt7921/mt7921-common.ko"
+      insmod_x "$EXTRA/mt76/mt7925/mt7925-common.ko"
+      insmod_x "$EXTRA/mt76/mt7921/mt7921e.ko"
+      insmod_x "$EXTRA/mt76/mt7925/mt7925e.ko"
+
+      # Patched bluetooth. The patched btmtk/btusb need symbols from the
+      # in-tree bluetooth core (bluetooth.ko) and the btrtl/btintel/btbcm
+      # helpers, so load those first (they are indexed and modprobe-able).
+      for m in bluetooth btrtl btintel btbcm rfkill ecdh_generic ecc crc16; do
+        if modprobe "$m" 2>/dev/null; then
+          echo "mt7927-force: modprobe $m ok"
+        else
+          echo "mt7927-force: modprobe $m FAILED (continuing)"
+        fi
+      done
+
+      insmod_x "$EXTRA/bluetooth/btmtk.ko"
+      insmod_x "$EXTRA/bluetooth/btusb.ko"
+    '';
+  };
+}

modules/hosts/14900k/configuration.nix

@@ -23,6 +23,7 @@
         ./_private/streaming-display.nix
         ./_private/ai.nix
         ./_private/media-disk.nix
+        ./_private/mediatek-mt7927.nix
         ./_private/jellyfin-nfs-export.nix
         ./_private/moonfin-flatpak.nix
       ];
@@ -44,7 +45,6 @@
           libvdpau-va-gl
         ];
       };
-
       environment.sessionVariables = {
         LIBVA_DRIVER_NAME = "iHD";
         # Force VA-API to use the Intel iGPU render node (otherwise libva may pick NVIDIA and iHD fails).