dumpyourvms: use systemd for disabling 2nd gpu,

hibernate when closing the lid, cleanup comments

hosts/dumpyourvms/dumpyourvms.nix

@@ -30,13 +30,18 @@ in {
       virtualisation.enable = true;
     };
 
-    # fix backlight for keyboard and brightness, adjust function key binding,
+    # Fix backlight for keyboard and brightness, adjust function key binding,
-    # intel_pstate for cpu schedutil, resume offset for swapfile, disable amdgpu driver
+    # intel_pstate for cpu schedutil
+    # For now, the radeon driver seems to work better than amdgpu with Radeon R9 M370X
+    # Explicitly set amdgpu support in place of radeon
+    # Source: https://github.com/NixOS/nixos-hardware/blob/master/common/gpu/amd/southern-islands/default.nix
+    # Try again after https://lists.freedesktop.org/archives/amd-gfx/2023-March/090096.html lands
+    # Maybe linux kernel 6.3?
+    #boot.kernelParams = ["acpi_backlight=video" "hid_apple.fnmode=2" "intel_pstate=passive" "radeon.si_support=0" "amdgpu.si_support=1"];
     boot.kernelParams = ["acpi_backlight=video" "hid_apple.fnmode=2" "intel_pstate=passive"];
     boot.loader.efi.canTouchEfiVariables = true;
-    #boot.resumeDevice = "/dev/mapper/cryptroot";
 
-    # fix for Error switching console mode to 1: unsupported on startup
+    # Fix for Error switching console mode to 1: unsupported on startup
     boot.loader.systemd-boot.consoleMode = mkForce "0";
 
     boot.binfmt.emulatedSystems = ["aarch64-linux"];
@@ -70,15 +75,36 @@ in {
 
     services.unbound = import ./unbound.nix;
 
-    # Disable dedicated GPU, use integrated Intel GPU to save battery
     # Set default brightness to 50%
     # https://ubuntuforums.org/showthread.php?t=2409856
     services.cron.systemCronJobs = [
       "@reboot root ${pkgs.util-linux}/bin/rfkill block bluetooth"
-      "@reboot root ${pkgs.coreutils}/bin/sleep 10; ${pkgs.coreutils}/bin/echo OFF > /sys/kernel/debug/vgaswitcheroo/switch"
       "@reboot root ${pkgs.coreutils}/bin/sleep 11; ${pkgs.coreutils}/bin/echo 510 > /sys/class/backlight/gmux_backlight/brightness"
     ];
 
+    # Disable dedicated GPU, use integrated Intel GPU to save battery
+    # https://github.com/NixOS/nixpkgs/pull/33915
+    systemd.services."amd-hybrid-graphics" = {
+      path = [pkgs.bash];
+      description = "Disable AMD Card";
+      after = ["sys-kernel-debug.mount"];
+      before = ["systemd-vconsole-setup.service" "display-manager.service"];
+      requires = ["sys-kernel-debug.mount" "vgaswitcheroo.path"];
+      serviceConfig = {
+        Type = "oneshot";
+        RemainAfterExit = true;
+        ExecStart = "${pkgs.bash}/bin/sh -c 'echo -e \"IGD\\nOFF\" > /sys/kernel/debug/vgaswitcheroo/switch'";
+        ExecStop = "${pkgs.bash}/bin/sh -c 'echo ON >/sys/kernel/debug/vgaswitcheroo/switch'";
+      };
+    };
+    systemd.paths."vgaswitcheroo" = {
+      pathConfig = {
+        PathExists = "/sys/kernel/debug/vgaswitcheroo/switch";
+        Unit = "amd-hybrid-graphics.service";
+      };
+      wantedBy = ["multi-user.target"];
+    };
+
     # Increase console font size for HiDPI display
     console = {
       earlySetup = true;
@@ -102,8 +128,8 @@ in {
       powerDownCommands = lib.mkBefore "${pkgs.kmod}/bin/rmmod brcmfmac";
     };
 
-    # change lid switch behaviour
+    # Change lid switch behaviour
-    #services.logind.lidSwitch = "hibernate";
+    services.logind.lidSwitch = "hibernate";
 
     # TLP for power management
     services.tlp = {
@@ -142,8 +168,6 @@ in {
     };
 
     # WLAN frequency compliance (e.g. check for radar with DFS)
-    #
-    # Radeon driver seems to work better than amdgpu with Radeon R9 M370X
     hardware.firmware = with pkgs; [wireless-regdb];
     boot.extraModprobeConfig = ''
       options cfg80211 ieee80211_regdom="DE"