https://bugs.kde.org/show_bug.cgi?id=478921
Bug ID: 478921
Summary: Black/Blurred screen on Plasma/KWin 6.0 Beta 1 +
Wayland + AMD iGPU + eGPU
Classification: Plasma
Product: kwin
Version: git master
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: fxzj...@163.com
Target Milestone: ---
(Originally posted at
https://discuss.kde.org/t/black-blurred-screen-on-plasma-kwin-6-0-beta-1-wayland-amd-egpu/8947
)
SUMMARY
Running KDE 6.0 Beta 1 recently on an AMD laptop, on Wayland session the screen
attached to external GPU cannot display properly on default, it cannot show any
part of a window if I drag one to it from the internal display (internal
display works normally), only random blurred/fuzzy screen or black screen.
STEPS TO REPRODUCE
1. Compile, install KDE Plasma 6.0 Beta 1
2. Run wayland session of it, with external screens attached to eGPU
OBSERVED RESULT
* random blurred/fuzzy screen or black screen on external monitor
* internal display works normally
EXPECTED RESULT
* all screens work
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu 22.04
KDE Plasma Version: 5.90.90
KDE Frameworks Version: 5.247.0
Qt Version: 6.6.2
ADDITIONAL INFORMATION
GPU setup:
```
➜ ~ lspci | grep VGA
37:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Vega
20 [Radeon VII] (rev c1)
63:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
Rembrandt (rev d8)
```
The eGPU Radeon VII is `/dev/dri/card0` and the iGPU Radeon 680M (of a Ryzen
6800HS) is `/dev/dri/card1`.
Driver is the one in upstream kernel, tried kernel version
`6.6.7-1-liquorix-amd64` and `6.5.0-1010-oem` (of Ubuntu 22.04)
Other behaviors noticed:
* Mouse cursor can be displayed properly on the external screen (which seems
strange?)
* Spectacle can capture all desktops correctly.
* No kernel/driver panic or warning in kernel message
* this phenomenon does not appear on Xorg session
* this phenomenon does not appear on KDE Plasma/KWin 5.27.x
* In accordance with this post ( [Plasma breaks on Wayland with NVIDIA
proprietary drivers
eGPU](https://discuss.kde.org/t/plasma-breaks-on-wayland-with-nvidia-proprietary-drivers-egpu/8749)
), the default setup seems equivalent to `export
KWIN_DRM_DEVICES=/dev/dri/card1:/dev/dri/card0`, and swapping them fixes it.
Current workaround: Use eGPU to render: add
```
export KWIN_DRM_DEVICES=/dev/dri/card0:/dev/dri/card1
```
to `$KDE_PREFIX/usr/lib/x86_64-linux-gnu/libexec/plasma-dev-prefix.sh`.
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