https://bugs.kde.org/show_bug.cgi?id=526339
Bug ID: 526339
Summary: KWin Wayland freezes when HDMI display enters DPMS
after inactivity on Intel i915
Classification: Plasma
Product: kwin
Version First 6.6.6
Reported In:
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-drm
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 196621
--> https://bugs.kde.org/attachment.cgi?id=196621&action=edit
KWin/Wayland DPMS freeze at 18:43:20 on September 27, 2026. Combined
user-session and DRM/i915 journal information from the reproducible failure.
KWin/Plasma intermittently freezes when the external HDMI display enters the
power-saving state after approximately 15 minutes of inactivity.
System:
* Ubuntu Studio 26.04
* KDE Plasma 6
* KWin 6.6.6
* Wayland
* Kernel 7.0.0-34-generic
* Intel Iris Plus / UHD Graphics (Ice Lake, GT1)
* i915 kernel driver
* Mesa 26.0.8-1ubuntu0.3
* External display: HDMI-A-1, 1920x1080 @ 60 Hz
* Internal display: eDP-1, connected but disabled
The problem can be reproduced intermittently.
After approximately 15 minutes of inactivity, when the display is supposed to
enter the power-saving state, the screen goes dark and immediately comes back
on. At the same moment, Plasma/KWin becomes frozen.
A reproduction occurred on September 27, 2026 at 18:43:20.
The journal shows the following sequence at exactly that time:
qt.qpa.wayland: There are no outputs - creating placeholder screen
kde.plasmashell: requesting unexisting screen available rect -1
kwin_wayland_drm: Atomic modeset test failed! Invalid argument
The "Atomic modeset test failed!" message occurred four times.
After the failure, KScreen still reported the HDMI output as connected and
enabled:
HDMI-A-1: connected, enabled, 1920x1080 @ 60 Hz
The internal eDP-1 output remained connected but disabled.
There are no corresponding i915 GPU hang, reset, or DRM error messages in the
kernel journal at the time of the failure.
A previous occurrence also produced:
kwin_scene_opengl: GL_INVALID_VALUE in glTexSubImage2D(xoffset 0 + width 1920 >
1856)
The problem does not happen on every power-saving cycle, but the failure is
reproducible intermittently when the display enters and immediately leaves the
power-saving state.
This appears to be related to KWin's DRM/atomic modesetting handling during the
display power-management transition.
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