nvidia: fix backlight

host/Senko/configuration.nix

@@ -24,6 +24,7 @@
 
   hardware.bluetooth.enable = true;
   host.laptop = true;
+  host.nvidia.prime.enable = true;
 
   environment.systemPackages = [ pkgs.dbgate ];
 }

host/modules/common.nix

@@ -7,7 +7,23 @@
   ];
 
   options = {
-    host.laptop = lib.mkEnableOption "laptop mode";
+    host = {
+      laptop = lib.mkEnableOption "laptop mode";
+
+      nvidia.prime = {
+        enable = lib.mkEnableOption "NVIDIA PRIME offload for hybrid graphics";
+        intelBusId = lib.mkOption {
+          type = lib.types.str;
+          default = "PCI:0:2:0";
+          description = "Intel/iGPU Bus ID used by NVIDIA PRIME.";
+        };
+        nvidiaBusId = lib.mkOption {
+          type = lib.types.str;
+          default = "PCI:1:0:0";
+          description = "NVIDIA dGPU Bus ID used by NVIDIA PRIME.";
+        };
+      };
+    };
   };
 
   config = {

host/modules/gpu/nvidia.nix

@@ -1,6 +1,16 @@
-{ config, pkgs-stable, lib, ... }: {
+{ config, pkgs-stable, lib, ... }: let
-  boot.kernelParams = [ "nvidia-drm.modeset=1" ];
+  primeCfg = config.host.nvidia.prime;
-  services.xserver.videoDrivers = [ "nvidia" ];
+  isPrimeOffload = primeCfg.enable;
+in {
+  boot = {
+    kernelParams = [ "nvidia-drm.modeset=1" ];
+    initrd.kernelModules = lib.optionals isPrimeOffload [ "i915" ];
+  };
+
+  services.xserver.videoDrivers =
+    if isPrimeOffload
+    then [ "modesetting" "nvidia" ]
+    else [ "nvidia" ];
 
   hardware = {
     graphics = {
@@ -11,7 +21,7 @@
         intel-media-driver
         libvdpau-va-gl
       ];
-      extraPackages32 = with pkgs-stable.pkgsi686Linux; [nvidia-vaapi-driver intel-media-driver];
+      extraPackages32 = with pkgs-stable.pkgsi686Linux; [ nvidia-vaapi-driver intel-media-driver ];
     };
 
     nvidia = {
@@ -24,21 +34,28 @@
       nvidiaSettings = true;
       package = config.boot.kernelPackages.nvidiaPackages.stable;
 
-      prime = lib.optionalAttrs config.host.laptop {
+      prime = lib.optionalAttrs isPrimeOffload {
-        intelBusId = "PCI:0:2:0";
+        offload = {
-        nvidiaBusId = "PCI:1:0:0";
+          enable = true;
+          enableOffloadCmd = true;
+        };
+        intelBusId = primeCfg.intelBusId;
+        nvidiaBusId = primeCfg.nvidiaBusId;
       };
     };
   };
 
   environment.sessionVariables = {
+    __GL_VRR_ALLOWED = 1;
+    ELECTRON_OZONE_PLATFORM_HINT = "auto";
+    NIXOS_OZONE_WL = 1;
+  } // lib.optionalAttrs isPrimeOffload {
+    LIBVA_DRIVER_NAME = "iHD";
+  } // lib.optionalAttrs (!isPrimeOffload) {
     WLR_NO_HARDWARE_CURSORS = 1;
     WLR_DRM_NO_ATOMIC = 1;
     GBM_BACKEND = "nvidia-drm";
     LIBVA_DRIVER_NAME = "nvidia";
     __GLX_VENDOR_LIBRARY_NAME = "nvidia";
-    __GL_VRR_ALLOWED = 1;
-    ELECTRON_OZONE_PLATFORM_HINT = "auto";
-    NIXOS_OZONE_WL = 1;
   };
 }