tmp.nix

{ pkgs, ... }:
{
  hardware.deviceTree = {
    filter = "bcm2711-rpi-*.dtb";
    overlays = [
      # Equivalent to:
      # https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/cma-overlay.dts
      {
        name = "rpi4-cma-overlay";
        dtsText = ''
          // SPDX-License-Identifier: GPL-2.0
          /dts-v1/;
          /plugin/;

          / {
            compatible = "brcm,bcm2711";

            fragment@0 {
              target = <&cma>;
              __overlay__ {
                size = <(${toString 512 /* FIXME: option ? */} * 1024 * 1024)>;
              };
            };
          };
        '';
      }
      # Equivalent to:
      # https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/vc4-fkms-v3d-overlay.dts
      {
        name = "rpi4-vc4-fkms-v3d-overlay";
        dtsText = ''
          // SPDX-License-Identifier: GPL-2.0
          /dts-v1/;
          /plugin/;

          / {
            compatible = "brcm,bcm2711";

            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";
              };
            };
          };
        '';
      }
    ];
  };
}