https://bugs.kde.org/show_bug.cgi?id=527163
Bug ID: 527163
Summary: Severe display corruption on Intel-connected monitor
with Intel + NVIDIA GPUs on Wayland after upgrading to
KWin 6.8.0
Classification: Plasma
Product: kwin
Version First 6.8.0
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-drm
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
DESCRIPTION
After upgrading from KDE Plasma 6.7.x to Plasma 6.8.0, I started experiencing
severe graphical corruption on a monitor connected to my Intel integrated GPU
in a multi-GPU NVIDIA + Intel Wayland setup.
The affected monitor is connected to the motherboard's Intel UHD Graphics 770
output. Four other monitors connected directly to the NVIDIA GeForce RTX 2070
SUPER work normally.
Symptoms on the Intel-connected monitor include:
1. Severe screen tearing and flickering
2. Triangles, fragments, and portions of application windows appearing in
unexpected places
3. Stale content from minimized, moved, or no-longer-visible windows
4. The mouse cursor sometimes disappearing or becoming horizontally chopped
when crossing between monitors
Spectacle screenshots and recordings look normal even while the corruption is
visible on the physical display (see attachment).
Important diagnostic observation: Moving the affected monitor's cable from the
motherboard output to the NVIDIA GPU completely eliminates the corruption.
The issue appeared immediately after upgrading to Plasma 6.8.0. To my
knowledge, the NVIDIA driver was not updated at the time.
Relevant graphics configuration:
Desktop: KDE Plasma 6.8.0
Window manager/compositor: KWin 6.8.0-1
Session: Wayland
Kernel: 7.2.9-arch1-1
Intel GPU: UHD Graphics 770 (Raptor Lake-S GT1), PCI 00:02.0, using i915
NVIDIA GPU: GeForce RTX 2070 SUPER, PCI 01:00.0, using the NVIDIA driver
NVIDIA driver: 615.78.08 (nvidia-open-dkms)
Mesa: 26.2.4-1
libdrm: 2.4.134-1
STEPS TO REPRODUCE
1. Use a multi-GPU system with Intel integrated graphics and an NVIDIA discrete
GPU, running KDE Plasma 6.8.0 on Wayland.
2. Connect one monitor to the Intel motherboard output and other monitors to
the NVIDIA GPU.
3. Log into the Plasma Wayland session and use the desktop normally.
4. Observe the Intel-connected monitor while moving the cursor between displays
and interacting with application windows.
OBSERVED RESULT
The Intel-connected monitor exhibits severe graphical corruption, including
flickering, tearing, misplaced window fragments, and stale image content. The
NVIDIA-connected monitors remain unaffected.
The cursor also becomes horizontally chopped or disappears when crossing
between displays.
Workarounds and tests performed:
- `KWIN_DRM_DISABLE_TRIPLE_BUFFERING=1`: no improvement.
- `KWIN_DRM_FORCE_MGPU_GL_FINISH=1`: no improvement.
- `KWIN_USE_OVERLAYS=0`: no improvement.
- `KWIN_FORCE_SW_CURSOR=1`: eliminates the cursor-chopping effect, but the
remaining display corruption persists.
- Moving the affected monitor from Intel to NVIDIA: eliminates all observed
corruption.
Spectacle captures do not show the corruption, despite it being clearly visible
on the physical display.
EXPECTED RESULT
All monitors should display the desktop correctly without tearing, flickering,
misplaced window fragments, stale content, or cursor corruption, regardless of
whether a monitor is connected to the Intel integrated GPU or the NVIDIA
discrete GPU.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.8.0
KDE Frameworks Version: 6.31.0
Qt Version: 6.12.0
Additional graphics and kernel versions:
KWin: 6.8.0-1
Kernel: 7.2.9-arch1-1
Mesa: 26.2.4-1
libdrm: 2.4.134-1
NVIDIA driver: 615.78.08 (nvidia-open-dkms)
ADDITIONAL INFORMATION
The issue started immediately after upgrading from Plasma 6.7.x to 6.8.0. I
have not yet established whether the regression is specifically in KWin or in
its interaction with the kernel and graphics drivers.
I can provide additional journal output and perform further diagnostic tests if
needed.
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