native: Add preferred-primary GPU selection via udev tag#811
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dongioia wants to merge 1 commit intolinuxmint:masterfrom
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native: Add preferred-primary GPU selection via udev tag#811dongioia wants to merge 1 commit intolinuxmint:masterfrom
dongioia wants to merge 1 commit intolinuxmint:masterfrom
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On multi-GPU SoCs like RK3588 (Rockchip), the mainline kernel exposes
two DRM devices: card0 (rockchip-drm, display-only, no 3D) and card1
(panthor, Mali-G610 GPU with full 3D). Muffin's choose_primary_gpu_unchecked()
selects the first platform device with render capability, which picks
card0 — a display controller with no OpenGL/Vulkan support.
This causes EGL clients to fall back to llvmpipe (software rendering),
as the compositor advertises the wrong device via wl_drm.
GNOME's Mutter solved this by introducing a udev tag mechanism
(mutter-device-preferred-primary) that lets system integrators
explicitly mark which GPU should be used as primary. This commit ports
that mechanism to Muffin using the tag "muffin-device-preferred-primary".
Changes:
- meta-udev.c/h: Add meta_is_udev_device_preferred_primary() that
checks for the "muffin-device-preferred-primary" udev tag
- meta-kms-types.h: Add META_KMS_DEVICE_FLAG_PREFERRED_PRIMARY flag
- meta-backend-native.c: Propagate the flag during GPU initialization
- meta-gpu-kms.c/h: Add meta_gpu_kms_is_preferred_primary() accessor
- meta-renderer-native.c: Check preferred_primary before platform_device
and boot_vga in choose_primary_gpu_unchecked()
Example udev rule for RK3588 boards:
SUBSYSTEM=="drm", KERNEL=="card1", DRIVERS=="panthor", \
TAG+="muffin-device-preferred-primary"
Tested on Rock 5B+ (RK3588) running BredOS with kernel 7.0-rc1 and
6.19.1, Cinnamon Wayland session. Verified that Muffin correctly
selects panthor (renderD128) as primary GPU with this patch applied.
Note: This fixes the compositor-side GPU selection (Part A). Full
client-side GPU discovery requires upgrading zwp_linux_dmabuf_v1
from v3 to v4+ with device feedback (Part B, separate work).
Ref: Mutter meta-udev.c meta_is_udev_device_preferred_primary()
Author
|
This PR addresses Part A of the issue described in linuxmint/wayland#194. See that issue for the full root cause analysis and the remaining Part B work (zwp_linux_dmabuf_v1 v4+ upgrade). |
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Summary
On multi-GPU SoCs like RK3588 (Rockchip), the mainline kernel exposes two DRM devices:
card0→rockchip-drm(display controller only, no 3D rendering)card1→panthor(Mali-G610 GPU, full OpenGL/Vulkan)Muffin's
choose_primary_gpu_unchecked()selects the first platform device with render capability, which pickscard0— a display controller with no OpenGL/Vulkan support. This causes all Wayland EGL clients to fall back to llvmpipe (software rendering).GNOME's Mutter solved this with a udev tag mechanism (
mutter-device-preferred-primary). This PR ports that mechanism to Muffin using the tagmuffin-device-preferred-primary.Changes
meta-udev.c/hmeta_is_udev_device_preferred_primary()— checks formuffin-device-preferred-primaryudev tagmeta-kms-types.hMETA_KMS_DEVICE_FLAG_PREFERRED_PRIMARYflagmeta-backend-native.cmeta-gpu-kms.c/hmeta_gpu_kms_is_preferred_primary()accessormeta-renderer-native.cTotal: +39 lines across 7 files. No behavioral change on systems without the udev tag.
Usage
System integrators add a udev rule to mark the 3D-capable GPU:
Testing
muffin-device-preferred-primarytag correctly detected viaudevadm info /dev/dri/card1renderD128(panthor) as primary GPU (verified via/proc/PID/fdand/sys/kernel/debug/dri/1/clients)Mali-G610 MC4 (Panfrost)✅Scope
This is Part A of a two-part fix for multi-GPU Wayland on Cinnamon:
zwp_linux_dmabuf_v1from v3 to v4+ withmain_devicefeedback, so that Wayland EGL clients know which render node to use. See related issue for details.Related
meta_is_udev_device_preferred_primary()zwp_linux_dmabuf_v1v4 feedback