https://bugs.kde.org/show_bug.cgi?id=527251
Bug ID: 527251
Summary: Regression: flickering/tearing on DisplayPort output
(Intel+Nvidia cross-GPU)
Classification: Plasma
Product: kwin
Version First 6.8.0
Reported In:
Platform: EndeavourOS
OS: Linux
Status: REPORTED
Keywords: regression
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 197219
--> https://bugs.kde.org/attachment.cgi?id=197219&action=edit
logs from a boot with flickering
DESCRIPTION
After updating from Plasma 6.7.5 to 6.8.0, I immediately noticed persistent
flickering/tearing artifacts on one of my two identical 75 Hz 1080p HP
monitors, which I had never seen before. The monitor connected via a USB-C
Thunderbolt-to-DisplayPort cable exhibited this flickering, but the one
connected via HDMI-to-HDMI did not, and connecting the cords to the opposite
monitors caused the flicker to follow the DP cable.
Workaround: I found that setting the following under plasma-workspace/env fixes
the flickering:
export KWIN_DRM_DEVICES=/dev/dri/card2:/dev/dri/card1
... where card1 is my Nvidia card and card2 is my iGPU. Swapping the order
(/dev/dri/card1:/dev/dri/card2) causes the same flickering behavior as I
initially observed.
STEPS TO REPRODUCE
1. On a system with Nvidia and Intel graphics, connect a monitor via
Thunderbolt/DisplayPort and start a Plasma session.
2. If you don't see any flickering, try setting KWIN_DRM_DEVICES to list the
Nvidia card first, followed by integrated. Log out and back in to apply the
change.
OBSERVED RESULT
Strange, persistent flickering/tearing artifacts on the DisplayPort-connected
monitor, especially when the content being displayed changes (e.g.
opening/closing/moving/windows, interacting with applications).
EXPECTED RESULT
No flickering.
SOFTWARE/OS VERSIONS
Operating System: EndeavourOS
KDE Plasma Version: 6.8.0
KDE Frameworks Version: 6.31.0
Qt Version: 6.12.0
Kernel Version: 7.2.10-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × Intel® Core™ i7-9750H CPU @ 2.60GHz
Memory: 32 GiB of RAM (31.1 GiB usable)
Graphics Processor 1: NVIDIA GeForce GTX 1660 Ti with Max-Q Design
Graphics Processor 2: Mesa Intel® UHD Graphics 630
ADDITIONAL INFORMATION
Previous KDE Plasma version: 6.7.5 (Wayland)
Nvidia driver: NVIDIA UNIX Open Kernel Module 615.78.08
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