https://bugs.kde.org/show_bug.cgi?id=527599
Bug ID: 527599
Summary: Severe visual glitches on external HDMI monitor
(NVIDIA dGPU) after updating to Plasma 6.8.1
Classification: Plasma
Product: kwin
Version First 6.8.1
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: grave
Priority: NOR
Component: core
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
DESCRIPTION
After the recent update to KDE Plasma 6.8.1, my external monitor connected via
HDMI (driven by the NVIDIA dGPU) exhibits severe visual glitches and
flickering.
The internal laptop screen and the external monitor connected via Thunderbolt
(Intel iGPU) work perfectly.
STEPS TO REPRODUCE
1. Connect an external monitor via HDMI (NVIDIA dGPU).
2. Boot into a Plasma Wayland session with Plasma 6.8.1.
3. Observe the HDMI monitor output.
OBSERVED RESULT
The HDMI external monitor shows severe visual glitches and flickering,
rendering it unusable.
EXPECTED RESULT
The HDMI external monitor should render the desktop correctly without visual
corruption, exactly as it did in Plasma 6.8.0.
SOFTWARE/OS VERSIONS
Operating System: CachyOS (Arch Linux based)
KDE Plasma Version: 6.8.1
ADDITIONAL INFORMATION
Troubleshooting already performed to isolate the issue:
- Tested older NVIDIA drivers (615.71.09 and 610.57.04). Verified with
nvidia-smi that they were loaded. The glitch persists on older drivers, ruling
out an NVIDIA driver regression.
- Rolled back the system via BTRFS snapshot to a working state (Plasma 6.8.0).
- Performed a partial system upgrade updating the Linux Kernel to 7.3.0 but
holding back the Plasma group (--ignoregroup=plasma).
- Result: The HDMI monitor works flawlessly with the new 7.3.0 kernel as long
as Plasma is kept at the older version. The regression is definitively tied to
the Plasma 6.8.1 / KWin update.
System Info / Hardware details:
https://paste.cachyos.org/p/e8d2d17.log
Attached is a short video demonstrating the visual glitches.
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