Nvidia `Disp.A: Off` and `[drm] Cannot find any crtc or sizes` error with Wayland (niri) using NVIDIA on NixOS

Help
1

Hello everyone,

I’m trying to configure my Nvidia GPU (RTX 3050) to be the primary GPU on NixOS (unstable), running the niri Wayland compositor but I keep getting the same error

The Problem:

Despite my configurations that I follow from Nvidia - NixOS Wiki, nvidia-smi consistently shows Disp.A: Off for the Nvidia GPU, and glxinfo | grep "OpenGL renderer string" reports the Intel GPU as the renderer.
The kernel log (dmesg) consistently shows the following error for the Nvidia GPU:
[drm] Cannot find any crtc or sizes

System Configuration (summary):

  • NixOS: (unstable)
  • Dedicated GPU: NVIDIA GeForce RTX 3050 (Driver: 570.144, CUDA: 12.8)
  • Integrated GPU: Intel (RPL-S)
  • Wayland Compositor: niri
  • Relevant Kernel Parameters: nvidia-drm.modeset=1 is active.

Snippets from configuration.nix:

# hardware.nvidia
hardware.nvidia.modesetting.enable = true;
hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.stable;

hardware.nvidia.prime = {
  // I've tried both 'sync.enable = true;' and 'reverseSync.enable = true;'
  // Currently using:
  sync.enable = true;
  intelBusId = "PCI:0:2:0";
  nvidiaBusId = "PCI:1:0:0";
};

// Niri session setup (to define WLR_DRM_DEVICES)
services.displayManager.sessionPackages = [
  (pkgs.stdenv.mkDerivation {
    name = "niri-session-with-nvidia";
    buildCommand = ''
      mkdir -p $out/share/wayland-sessions
      cat > $out/share/wayland-sessions/niri.desktop <<EOF
[Desktop Entry]
Name=Niri (Nvidia Primary)
Comment=Niri Wayland Compositor (Attempting Nvidia Primary)
Exec=env WLR_DRM_DEVICES="/dev/dri/by-path/pci-0000:01:00.0-card" ${pkgs.dbus}/bin/dbus-run-session -- ${pkgs.niri}/bin/niri
Type=Application
DesktopNames=niri
EOF
    '';
    passthru.providedSessions = [ "niri" ];
  })
];

// services.xserver.enable = true; // For XWayland support

 What I've tried so far:
  - Ensuring nvidia-drm.modeset=1 is set.
  - Setting WLR_DRM_DEVICES for the niri session to point to the Nvidia card.
  - Toggling between hardware.nvidia.prime.sync.enable = true; and hardware.nvidia.prime.reverseSync.enable = true;