SUMMARY With a dual monitor setup, some applications on the external display will make it flicker very hard. It flickers with google chrome (in wayland mode), it flickers with eclipse (in xwayland mode and not in wayland mode). With these two applications it is certain the display wilil flicker. It also flickers with KDE apps (okular, kmail, kate, etc), but with these apps it seems random, the screen starts to flicker without any input from my side STEPS TO REPRODUCE 1. Set up a laptop with an external display 2. open eclipse (GDK_BACKEND=x11 flag set) in the external display, and maximize the window 3. move the mouse around our right click on the mouse to access any pop up menu OBSERVED RESULT The screen start to flicker EXPECTED RESULT Steady image SOFTWARE/OS VERSIONS Operating System: Ubuntu 13 KDE Plasma Version: 6.4.91 KDE Frameworks Version: 6.18.0 Qt Version: 6.9.2 Kernel Version: 6.17.0-061700-generic (64-bit) Graphics Platform: Wayland Processors: 16 × AMD Ryzen 9 6900HX with Radeon Graphics Memory: 40 GiB of RAM (34,9 GiB usable) Graphics Processor 1: AMD Radeon 680M Graphics Processor 2: AMD Radeon RX 6800S Manufacturer: LENOVO Product Name: 82UG System Version: Legion S7 16ARHA7 I made a video with the spectacle screen recorder and it did no catch any flickering. But, at same time, I also made a video with my phone and the flicker is very visible.
It started with the first beta (6.5.90), but I waited for the beta 2 release to see if it was something that was missing out.
Created attachment 185478 [details] Video made with my phone This video was make with my phone since the video that was made with spetacle (at the same time) got no flickering
Created attachment 185479 [details] Link to video made with spectacle screen recorder Link to video made with spectacle screen recorder
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8198
(In reply to Bug Janitor Service from comment #4) > A possibly relevant merge request was started @ > https://invent.kde.org/plasma/kwin/-/merge_requests/8198 Hello! I applied the "backends/drm: clear the import damage journal after renderTestBuffer" commit on http://download.kde.org/unstable/plasma/6.4.91/kwin-6.4.91.tar.xz source package, compiled it, replaced the "kwin_wayland_wrapper" and "kwin_wayland" files by the new ones. The external display no longer flickers while running Eclipse or Kicad.
Git commit b952e59442f96ca89ff64ecaf4ad56f1d8c19ded by Xaver Hugl. Committed on 07/10/2025 at 10:47. Pushed by zamundaaa into branch 'master'. backends/drm: clear the import damage journal after renderTestBuffer Otherwise, the newly allocated buffer has an entry in the damage journal, which means it only gets partially repainted when drawing an actual frame. The result of that was heavy flickering, until that buffer got fully repainted. M +2 -0 src/backends/drm/drm_egl_layer_surface.cpp https://invent.kde.org/plasma/kwin/-/commit/b952e59442f96ca89ff64ecaf4ad56f1d8c19ded
Git commit 5a8f9117ae7d9b11f32b9c88ca3c8111b1a0d7c0 by Xaver Hugl. Committed on 07/10/2025 at 12:19. Pushed by zamundaaa into branch 'Plasma/6.5'. backends/drm: clear the import damage journal after renderTestBuffer Otherwise, the newly allocated buffer has an entry in the damage journal, which means it only gets partially repainted when drawing an actual frame. The result of that was heavy flickering, until that buffer got fully repainted. (cherry picked from commit b952e59442f96ca89ff64ecaf4ad56f1d8c19ded) Co-authored-by: Xaver Hugl <xaver.hugl@kde.org> M +2 -0 src/backends/drm/drm_egl_layer_surface.cpp https://invent.kde.org/plasma/kwin/-/commit/5a8f9117ae7d9b11f32b9c88ca3c8111b1a0d7c0