nixos-hardware/raspberry-pi/4/pkgs-overlays.nix

{ config, lib, pkgs, modulesPath, ... }:
let
  cfg = config.hardware.raspberry-pi."4".apply-overlays-dtmerge;
  dt_ao_overlay = (final: prev: {
    deviceTree.applyOverlays = (prev.callPackage ./apply-overlays-dtmerge.nix { })
  });
in {
  options.hardware = {
    raspberry-pi."4".apply-overlays-dtmerge = {
      enable = lib.mkEnableOption ''
        replace deviceTree.applyOverlays implementation to use dtmerge from libraspberrypi.
        this can resolve issues with applying dtbs for the pi.
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    nixpkgs.overlays = [ dt_ao_overlay ];
  };
}