fakeKMS for PI4

raspberry-pi/overlays/default.nix

@@ -9,6 +9,7 @@
     ./dtb-cpi-i2c1.nix
     ./dtb-cpi-bluetooth.nix
     ./dtb-vc4-kms-v3d.nix
+    ./dtb-vc4-fkms-v3d.nix
     ./dtb-cpi-spi4.nix
     ./dtb-rpi4-disable-pwrled.nix
   ];

raspberry-pi/overlays/dtb-vc4-fkms-v3d.nix

@@ -0,0 +1,30 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib) mkEnableOption mkIf mkMerge mkOption types;
+  cfg = config.hardware.raspberry-pi."4".overlays.vc4-fkms-v3d;
+in {
+  options.hardware.raspberry-pi."4".overlays.vc4-fkms-v3d = {
+    enable = mkEnableOption ''overlay enable'';
+    name = mkOption {
+      type = types.str;
+      default = "vc4-fkms-v3d";
+    };
+  };
+
+  config = mkMerge [
+    (mkIf cfg.enable {
+      hardware.deviceTree = {
+        overlays = [
+          {
+            name = "${cfg.name}";
+            filter = "bcm2711-rpi-*.dtb";
+            dtsFile = ./source/vc4-fkms-v3d.dts;
+          }
+        ];
+      };
+    })
+  ];
+}

raspberry-pi/overlays/source/vc4-fkms-v3d.dts

@@ -0,0 +1,69 @@
+/dts-v1/;
+/plugin/;
+
+&frag0 {
+	size = <((512-4)*1024*1024)>;
+};
+
+/ {
+	compatible = "brcm,bcm2711";
+
+	fragment@0 {
+		target = <&cma>;
+		frag0: __overlay__ {
+			/*
+			 * The default size when using this overlay is 256 MB
+			 * and should be kept as is for backwards
+			 * compatibility.
+			 */
+			size = <0x10000000>;
+		};
+	};
+
+	fragment@1 {
+		target = <&fb>;
+		__overlay__  {
+			status = "disabled";
+		};
+	};
+
+	fragment@2 {
+		target = <&firmwarekms>;
+		__overlay__  {
+			status = "okay";
+		};
+	};
+
+	fragment@3 {
+		target = <&v3d>;
+		__overlay__  {
+			status = "okay";
+		};
+	};
+
+	fragment@4 {
+		target = <&vc4>;
+		__overlay__  {
+			status = "okay";
+		};
+	};
+	fragment@5 {
+		target-path = "/chosen";
+		__overlay__  {
+			bootargs = "clk_ignore_unused";
+		};
+	};
+	__overrides__ {
+		cma-512 = <&frag0>,"size:0=",<0x20000000>;
+		cma-448 = <&frag0>,"size:0=",<0x1c000000>;
+		cma-384 = <&frag0>,"size:0=",<0x18000000>;
+		cma-320 = <&frag0>,"size:0=",<0x14000000>;
+		cma-256 = <&frag0>,"size:0=",<0x10000000>;
+		cma-192 = <&frag0>,"size:0=",<0xC000000>;
+		cma-128 = <&frag0>,"size:0=",<0x8000000>;
+		cma-96  = <&frag0>,"size:0=",<0x6000000>;
+		cma-64  = <&frag0>,"size:0=",<0x4000000>;
+		cma-size = <&frag0>,"size:0"; /* in bytes, 4MB aligned */
+		cma-default = <0>,"-0";
+	};
+};