https://bugs.kde.org/show_bug.cgi?id=488299
Bug ID: 488299
Summary: Plasma wayland session becomes unresponsive when
attaching external screens
Classification: Plasma
Product: kwin
Version: 5.27.11
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
When attaching multiple external screens via MST over USB-C (DP alt mode, no
thunderbolt/USB 4) with Plasma running in wayland mode the session will become
unresponsive.
The unresponsive state can be described as following: The external screens will
not show any image, but report "No Signal". They will still come out of
standby. The internal screen will continue to show the image active before
connecting the external screens. The image on the internal screen is
non-responsive to any inputs (Mouse, Keyboard). When the external screens are
disconnected, the internal screen will start working normally again.
It seems like Plasma is actually working on rearranging the windows on display
after disconnecting the external screens. Also sound continues like normal. No
Plasma components seem to crash (most of the time). So it seems like Plasma is
actually continuing to work but not displaying any updates on any screen.
STEPS TO REPRODUCE
1. Connect device to MST hub via USB-C
2. Observe screens
OBSERVED RESULT
Plasma session becomes visually unresponsive but seems to continue to work in
the background.
EXPECTED RESULT
Plasma session continues normally on the connected screens.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kernel 6.8.0-35-generic on Kubuntu 24.04
(available in About System)
KDE Plasma Version: 5.27.11
KDE Frameworks Version: 5.115.0
Qt Version: 5.15.13
ADDITIONAL INFORMATION
This behaviour is exclusive to plasma in wayland mode. X11 works as expected,
so does GNOME in wayland mode on the same machine. It seems that this issue
also only occurs on one specific laptop for me (Framework Laptop 13" with AMD
Ryzen 5 7640U). The same setup with an old HP EliteBook 1030 G3 (Some 8th gen
i5) is working fine, even with the same SSD. The issue is also persistent
across multiple distros (Tested with Debian, Fedora, Manjaro and Ubuntu).
The hardware in use:
- Framework Laptop 13" with AMD Ryzen 5 7640U
- Two Samsung S27A600UUU displays.
Hardware configuration:
- The laptop is connected to one of the displays via USB-C. This connection
carries USB 2, DP and Power (60W)
- The first display is connected to the second display via DP. This only
carries a DP signal
- The first display is put into MST mode, so that the two screens can display
separate images
Please note that I only tested connecting screens via USB-C as I do not have
any other possibility of connecting displays. I also did not try another MST
hub (I think I have 2 somewhere here). If helpful, I can try a few more
combinations of those.
Additionally, as this is not a crash, I do not know which logs to attach, but
will gladly contribute anything that might help.
--
You are receiving this mail because:
You are watching all bug changes.
