https://bugs.kde.org/show_bug.cgi?id=508928
Bug ID: 508928
Summary: DisplayLink USB monitor: Severe performance lag on KDE
Wayland due to framebuffer creation errors
Classification: Plasma
Product: kwin
Version First 6.4.4
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 184578
--> https://bugs.kde.org/attachment.cgi?id=184578&action=edit
system_info.txt
Severe performance lag on DisplayLink USB monitor under KDE Wayland due to
framebuffer creation errors.
STEPS TO REPRODUCE
Connect a DisplayLink USB monitor to a system running KDE Plasma on a
Wayland session.
Observe the performance of the display (e.g., moving a window, scrolling in
a browser).
OBSERVED RESULT
The display output is extremely laggy, with a very low refresh rate and high
latency, making the monitor nearly unusable. The system journal shows a
continuous error: kwin_wayland_drm: Failed to create a framebuffer: Invalid
argument. The evdi kernel module is loaded and the displaylink.service is
active.
EXPECTED RESULT
Performance should be adequate for basic desktop tasks, comparable to the
experience on an X11 session or Windows, utilizing hardware acceleration.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: CachyOS
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.1
ADDITIONAL INFORMATION
The same hardware functions correctly on a Plasma X11 session and Windows,
proving it is a software integration issue specific to Wayland.
The journal is flooded with the framebuffer error. The full log output from
journalctl -b -0 -g "displaylink|evdi|kwin" --no-pager is attached.
This is distinct from other reported issues about fullscreen compositing
(e.g., bug #XXXXX). This bug occurs globally on the DisplayLink monitor and is
triggered by the presence of the device itself, not by entering fullscreen.
Attachments: kwin_displaylog_log.txt, system_info.txt
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