https://bugs.kde.org/show_bug.cgi?id=461743
Bug ID: 461743
Summary: iGPU multi-monitor: Part of screen missing on
secondary (integrated GPU)
Classification: Plasma
Product: kwin
Version: 5.26.3
Platform: Gentoo Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 153696
--> https://bugs.kde.org/attachment.cgi?id=153696&action=edit
iGPU connected monitor on 1440x900@75
SUMMARY
I recently replaced my (AMD) GPU with an Intel Arc. Unfortunately my
motherboard does not like booting from it for weird reasons. This means I am
(still) stuck using the integrated GPU as boot GPU and therefore require the
dual-GPU multi-monitor feature. Though this used to work fine with the AMD dGPU
+ Intel iGPU combination, the Intel dGPU + Intel iGPU combination is producing
a weird screen artefact on the monitors connected to the iGPU (see attached
photo). SDDM (which runs in X on the iGPU) renders fine. The mouse does
actually move over the missing black area, and I can even interact with buttons
which are hidden by the black part. If I cycle through the supported
resolutions the black area changes, and for specific resolutions even goes
away.
The problem is not with the monitor, cable, or output. I tested a different
cable with a different monitor, on a DV-D instead of VGA output and got the
exact same result.
This might be a mesa rendering bug instead of a kwin bug?
There is also a separate issue where kscreen/kwin sometimes does not list all
supported resolutions/refresh rates for monitors connected to the Intel dGPU
(e.g. 80, 100, 144 is missing, 60 is the highest option). However. I have not
yet found the exact conditions that produce that bug, and it feels more like a
kernel level problem so it might not be relevant here.
STEPS TO REPRODUCE
1. Enable Multi-Monitor in BIOS on a Intel dGPu, Intel iGPU system
2. Connect a display to the dGPU and iGPU
3. Start a wayland session
OBSERVED RESULT
The bottom part of the monitors connected to the iGPU is "hidden" by a weird
black part.
EXPECTED RESULT
The full display is visible
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo Linux (kernel 6.0.8, mesa 22.2.3)
KDE Plasma Version: 5.26.3
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.5
ADDITIONAL INFORMATION
Intel i9-9900KS UHD Graphics 630 (CFL GT2) + Intel Arc A770 Graphics (DG2)
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