SUMMARY After updating to 6.3.1 whenever the mouse cursor moves between two displays (or just touches the edge between them) while a fullscreen application (Firefox in fullscreen, or any game, native or through Wine/Proton), the screen will very briefly flash white. This only appears to happen on Wayland. Enabling or disabling VRR on one or both displays doesn't seem to have any effect on this. The only workaround I have found so far is to turn off the secondary display when playing a game to prevent the very unpleasant flickering. This did not happen on versions up to and including 6.3.0. STEPS TO REPRODUCE 1. Launch Firefox and set it to fullscreen, or any game that doesn't strictly confine the mouse cursor 2. Move the cursor into the secondary screen 3. Move the cursor back to the primary display OBSERVED RESULT Whenever the cursor transitions between the screen the primary display with show a brief, bright flash. EXPECTED RESULT Display doesn't flicker when the cursor moves between screens when fullscreen applications are open. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Arch Linux KDE Plasma Version: 6.3.1 KDE Frameworks Version: 6.11.0 Qt Version: 6.8.2 ADDITIONAL INFORMATION Using an AMD GPU with Mesa drivers
Does this still happen if you put KWIN_DRM_NO_DIRECT_SCANOUT=1 into /etc/environment and reboot?
(In reply to Zamundaaa from comment #1) > Does this still happen if you put KWIN_DRM_NO_DIRECT_SCANOUT=1 into > /etc/environment and reboot? Set the environment variable and the flicker no longer occurs. Tried it with fullscreen Firefox, Haruna and a game and there's no more flashing when moving the cursor between displays.
After some quick tests it looks like this has been fixed with KWin 6.3.2.1
Unfortunately after more retesting the flashing is still present and I had to revert back to using KWIN_DRM_NO_DIRECT_SCANOUT=1
Was experiencing the same issue and disabling the color profile resolved the issue. Re-enabling the ICC profile on the screen displaying fullscreen content causes it to flicker again. I am using the built-in profile on both displays (which may not be 100% accurate, but looks more accurate than stock settings to the naked eye)
Further testing, it also occurs if Night Light is active even without an ICC profile enabled on the display. Also using AMD GPU, latest mesa built from git just now.
Removed the KWIN_DRM_NO_DIRECT_SCANOUT=1 environment variable, disabled night light and the flashing is gone. Would explain why it didn't happen during my initial tests. Double checked I'm not using any ICC settings just to be sure.
Last bit of spam on this. I pulled one of my old monitors out of the closet so I could test using my current setup of 2x Dell G2724D's (both HDR400 capable but running in SDR) and add my old Dell 2421HS (SDR) Interestingly I could *not* reproduce the issue in the mixed monitor environment at all. I tried both dual monitor and triple monitor. The flashing did not occur with either G2724D as long as the 2421HS was connected/enabled . The mere presence of an SDR-only monitor seems to fix the flashing. Video of the above: https://www.youtube.com/watch?v=fQMZzbz2N-g Description: Moving cursor between monitors without flashing before disabling SDR monitor. Flashing visible when moving cursor between screens The flashing does not occur if the G2724D playing fullscreen content has HDR enabled, and does not occur at all on the SDR only monitor.
Having the same issue, but also when playing video with mpv in fullscreen the screen also flickers when the mouse disappears and reappears. Interestingly, I have "shake cursor" enabled, and if I shake the cursor to magnify it and then move it to the other screen the flicker doesn't happen until the cursor returns to its normal size.
I don't see this issue on my AMD laptop or desktop PC, with a second display connected or without - switching between direct scanout and compositing doesn't have any visual difference or glitches. Can I get some more details on what hardware you're on? The GPU model and the output of kscreen-doctor -o specifically (In reply to nyikoszoltan0 from comment #9) > Interestingly, I have "shake cursor" enabled, and if I shake the cursor to > magnify it and then move it to the other screen the flicker doesn't happen > until the cursor returns to its normal size. That's because the effect inhibits direct scanout while it's active.
Created attachment 179280 [details] kscreendoctor output I am using a 7700XT. The only difference between the kscreendoctor ouput with or without the 1080p monitor is geometry/enabled/priority values.
Created attachment 179313 [details] kscreen-doctor output Just updated to kwin 6.3.3 and I'm still experiencing flashing if night light is enabled. Using an AMD Radeon 7900XTX.
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME. For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging. Thank you for helping us make KDE software even better for everyone!
Created attachment 179873 [details] kscreen-doctor output Same issue OS: ArchLinux Plasma: 6.3.3 Kernel: 6.13.8 Mesa: 25.0.2 GPU: AMD Radeon 7900XTX 1. Night Light is active (gamma is adjusted) 2. Open a fullscreen window (Fullscreen YouTube video in Firefox, for example) - doesn't matter if on primary or secondary screen. 3. Move cursor to the other screen, then back, repeat 4. Flashing observed as soon as cursor enters and leaves the monitor with the fullscreen window. It appears that the gamma filter is removed from the picture for a brief moment.
The issue persists in version 6.3.4.
Also reproduces on kernel 6.14 Went compiled old versions to check, was introduced in 6.3.1 and was not present in 6.3.0. Used v6.3.0 and v6.3.1 as good/bad and bisected to 5453662f9cd4816e4b046beb0c7df5a676a3df7c is the first bad commit commit 5453662f9cd4816e4b046beb0c7df5a676a3df7c Author: Xaver Hugl <xaver.hugl@gmail.com> Date: Fri Feb 14 16:43:36 2025 +0100 backends/drm: fix KMS offloading with scaling We apply scaling in most cases to normalize values to [0; 1], so the check for input values > 1 was often wrongly preventing KMS offloading. (cherry picked from commit 4205a9b9423d08678483b5c6fa7da2dc5ed29628) Also on closer inspection it's not strictly a bright flicker, it's dark flicker as well. The frame on entering scanout is too bright, in addition to the frame on exiting scanout being too dark.
On my setup, whether this issue occurs appears to be linked to the kernel version. I have been able to consistently reproduce it on 6.14.1 and 6.15-rc1, but for me, it does not happen on 6.13.8 as some users reported, or 6.12-lts. I am using a different GPU though. KDE 6.3.4 Arch Linux Radeon 9070XT