https://bugs.kde.org/show_bug.cgi?id=521814

adri365 <[email protected]> changed:

           What    |Removed                     |Added
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                 CC|                            |[email protected]

--- Comment #31 from adri365 <[email protected]> ---
I can confirm that `KWIN_RENDER_NODES` successfully resolves the NVIDIA dGPU
runtime power management issue on my HP OMEN 16 with hybrid AMD/NVIDIA
graphics.

**System configuration:**
- Laptop: HP OMEN 16-ap0007ns
- CPU: AMD Ryzen AI 7 350
- Integrated GPU: AMD Radeon 860M
- Dedicated GPU: NVIDIA GeForce RTX 5070 Laptop (8 GB)
- Distribution: Kubuntu 26.04
- KDE Plasma / KWin: 6.7.5
- Qt: 6.11.2
- Mesa: 26.2.4
- Linux kernel: 7.3.0-9-generic
- NVIDIA driver: 580.178.04
- Display server: Wayland

**Before applying the workaround:**

KWin correctly rendered the desktop using the AMD Radeon 860M, but the NVIDIA
RTX 5070 remained in D0 (active).

Stopping both `nvidia-powerd` and `omen-space-daemon` did not resolve the
issue. KWin was still accessing the NVIDIA devices.

**Workaround:**

I configured the following environment variable for the
`plasma-kwin_wayland.service` systemd user unit:

`KWIN_RENDER_NODES=/dev/dri/by-path/pci-0000:06:00.0-card`

This restricts KWin's directly opened render nodes to the AMD GPU.

**Results:**

- The NVIDIA RTX 5070 successfully enters D3cold.
- Runtime power management reports `suspended`.
- The desktop continues rendering correctly using the Radeon 860M.
- Both `nvidia-powerd` and `omen-space-daemon` remain active.
- Running `nvidia-smi` wakes the NVIDIA GPU to D0.
- Closing `nvidia-smi` allows it to return to D3cold within a few seconds.
- A direct CUDA Driver API test successfully initialized CUDA, created a
context, allocated 128 MB of VRAM and performed a device memory operation.
- After destroying the CUDA context and exiting the application, the RTX 5070
automatically returned to D3cold.

Interestingly, `kwin_wayland` still appears among the processes accessing
NVIDIA device files, even while the GPU successfully enters D3cold.

This confirms that the `KWIN_RENDER_NODES` workaround enables proper NVIDIA
runtime power management on this recent AMD/NVIDIA hybrid laptop without
disabling CUDA or NVIDIA services.

Thank you for implementing this option!

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