https://bugs.kde.org/show_bug.cgi?id=527806
Bug ID: 527806
Summary: Short black flash on monitor when focusing or opening
windows since 6.8.1; KWIN_USE_OVERLAYS=0 fixes it
Classification: Plasma
Product: kwin
Version First 6.8.1
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-drm
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
SUMMARY
Since upgrading from Plasma/KWin 6.8.0 to 6.8.1, one of my monitors goes black
for a moment
when I focus a window or open an application. It happens on both monitors.
Setting
KWIN_USE_OVERLAYS=0 stops the flashes completely, so it looks like a problem
with
overlay plane assignment/offloading.
STEPS TO REPRODUCE
1. Plasma Wayland session, two monitors on an AMD RX 9070 XT (details below)
2. Click between windows to change focus, or launch an application
3. Watch the monitor showing the window
OBSERVED RESULT
The monitor goes black for a moment (well under a second), then shows the
correct
image. It happens often during normal use. Nothing gets logged in the journal
or the
kernel log (no DRM/amdgpu errors, no commit failures).
EXPECTED RESULT
No flashing.
WORKAROUND
Add KWIN_USE_OVERLAYS=0 in ~/.config/environment.d/ and log in again. Since
then I've
had no flashes at all.
REGRESSION INFO
- First noticed the evening of 2026-10-24, right after the upgrade that took
kwin 6.8.0-1.1 -> 6.8.1-2.1 (CachyOS packages), along with the rest of Plasma
6.8.1
(kscreen, libkscreen, powerdevil, plasma-workspace, ...).
- Mesa was upgraded in the same transaction (26.2.4 -> 26.2.5), so I can't
fully
rule out Mesa. The fact that disabling overlays in KWin fixes it points to
KWin's
overlay path, though.
- Not related to the color power preference: it still happened with the setting
on
"accuracy" and on "efficiency".
SOFTWARE/OS VERSIONS
Distro: CachyOS (Arch-based)
KDE Plasma: 6.8.1
KWin: 6.8.1-2.1
Qt: 6.12.0
Mesa: 26.2.5
libdrm: 2.4.134
Kernel: 7.3.0-4-cachyos (6.18.55 LTS also installed)
Graphics platform: Wayland
HARDWARE
GPU: AMD Radeon RX 9070 XT (Navi 48, 1002:7550), amdgpu
Monitors:
- DP-2: 2560x1440 @ 144 Hz (primary)
- HDMI-A-1: 1920x1080 @ 144 Hz
Both: scale 1, VRR off, no HDR/WCG, 10 bpc auto, sRGB, DDC/CI brightness at
100%
ADDITIONAL INFORMATION
Happy to test patches or collect KWin debug output (e.g.
QT_LOGGING_RULES="kwin_wayland_drm*=true")
if it helps.
Possibly related, but probably not the same bug: bug 527591 (6.8.1 regression
on NVIDIA hybrid setups;
this machine is single-GPU AMD), bug 527421 (legacy-modesetting offload fix;
amdgpu uses atomic), and
bug 527776 (6.8.1 external screen flicker with lasting artifacts).
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