nixos/nvidia: use kernel suspend notifiers if available

Author: ccicnce113424

nixos/modules/hardware/video/nvidia.nix

@@ -88,10 +88,19 @@ in
         the NVIDIA docs, on Chapter 21. Configuring Power Management Support
       '';
 
-      powerManagement.finegrained = lib.mkEnableOption ''
-        experimental power management of PRIME offload. For more information, see
-        the NVIDIA docs, on Chapter 22. PCI-Express Runtime D3 (RTD3) Power Management
-      '';
+      powerManagement.kernelSuspendNotifier =
+        lib.mkEnableOption ''
+          NVIDIA driver support for kernel suspend notifiers, which allows the driver
+          to be notified of suspend and resume events by the kernel, rather than
+          relying on systemd services.
+          Requires NVIDIA driver version 595 or newer, and the open source kernel modules.
+        ''
+        // {
+          default = useOpenModules && lib.versionAtLeast nvidia_x11.version "595";
+          defaultText = lib.literalExpression ''
+            config.hardware.nvidia.open == true && lib.versionAtLeast config.hardware.nvidia.package.version "595"
+          '';
+        };
 
       dynamicBoost.enable = lib.mkEnableOption ''
         dynamic Boost balances power between the CPU and the GPU for improved
@@ -465,6 +474,13 @@ in
               assertion = cfg.dynamicBoost.enable -> lib.versionAtLeast nvidia_x11.version "510.39.01";
               message = "NVIDIA's Dynamic Boost feature only exists on versions >= 510.39.01";
             }
+
+            {
+              assertion =
+                cfg.powerManagement.kernelSuspendNotifier
+                -> (useOpenModules && lib.versionAtLeast nvidia_x11.version "595");
+              message = "NVIDIA driver support for kernel suspend notifiers requires NVIDIA driver version 595 or newer, and the open source kernel modules.";
+            }
           ];
 
           # If Optimus/PRIME is enabled, we:
@@ -576,7 +592,9 @@ in
               ''
             );
 
-          systemd.packages = lib.optional cfg.powerManagement.enable nvidia_x11.out;
+          systemd.packages = lib.optional (
+            cfg.powerManagement.enable && !cfg.powerManagement.kernelSuspendNotifier
+          ) nvidia_x11.out;
 
           systemd.services =
             let
@@ -592,7 +610,7 @@ in
               };
             in
             lib.mkMerge [
-              (lib.mkIf cfg.powerManagement.enable {
+              (lib.mkIf (cfg.powerManagement.enable && !cfg.powerManagement.kernelSuspendNotifier) {
                 nvidia-suspend = nvidiaService "suspend";
                 nvidia-hibernate = nvidiaService "hibernate";
                 nvidia-resume = (nvidiaService "resume") // {
@@ -669,6 +687,9 @@ in
               ++ lib.optional (
                 (offloadCfg.enable || cfg.modesetting.enable) && lib.versionAtLeast nvidia_x11.version "545"
               ) "nvidia-drm.fbdev=1"
+              ++ lib.optional (
+                cfg.powerManagement.enable && cfg.powerManagement.kernelSuspendNotifier
+              ) "nvidia.NVreg_UseKernelSuspendNotifiers=1"
               ++ lib.optional cfg.powerManagement.enable "nvidia.NVreg_PreserveVideoMemoryAllocations=1"
               ++ lib.optional useOpenModules "nvidia.NVreg_OpenRmEnableUnsupportedGpus=1"
               ++ lib.optional (config.boot.kernelPackages.kernel.kernelAtLeast "6.2" && !ibtSupport) "ibt=off";