SUMMARY "Full screen repaints" is not honored after reboot. STEPS TO REPRODUCE 1. Open "System Settings > Display and Monitor > Compositor" 2. Set "Tearing prevention" to "Full screen repaints" 3. Reboot the PC. OBSERVED RESULT Windows visibly tear. EXPECTED RESULT "Full screen repaints" prevents tearing. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Kubuntu 18.04 (available in About System) KDE Plasma Version: 5.12.7 KDE Frameworks Version: 5.44.0 Qt Version: 5.9.5 ADDITIONAL INFORMATION Workaround: go through steps 1-2 again, and tearing stops.
Please post output of `qdbus org.kde.KWin /KWin supportInformation` before and after applying the workaround. Also, out of curiosity, why do you want full screen repaints? :-)
> Also, out of curiosity, why do you want full screen repaints? :-) Because without this setting, the windows tearing hurts my eyes. > Please post output of `qdbus org.kde.KWin /KWin supportInformation` before and after applying the workaround. I'll try to get this next time I reboot.
Created attachment 119848 [details] qdbus org.kde.KWin /KWin supportInformation output before applying workaround
Created attachment 119850 [details] qdbus org.kde.KWin /KWin supportInformation output after applying workaround Added two attachments. Output of qdbus before and after applying workaround.
Hmm, looks like compositing is not enabled by default. If you enable compositing as well set tearing prevention back to "Automatic", does screen tearing occur?
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> If you enable compositing as well set tearing prevention back to "Automatic", does screen tearing occur? With the "Automatic" settings, the screen tearing does not occur. Thank you for fixing my setup — turns out I didn't actually need "Full screen repaints". Off-topic: It would seem that the *UX* for checkbox "Enable compositor on startup" could be improved. It was not clear at all to me, that all the settings below this checkbox depend on it being turned on. I would have expected for this checkbox to get selected automatically when you change anything else on that screen. Especially since "compositor" actually turns itself on automatically when you touch these settings (as logs in the comment above have shown). Another possible approach would be to show a big warning at the bottom of the dialog (near "Apply" button): > The settings will be reset on restart, if you don't check the checkbox "Enable compositor on startup".
Setting "Enable compositor on startup" still breaks sometimes in 5.19.5 Operating System: KDE neon 5.19 KDE Plasma Version: 5.19.5 KDE Frameworks Version: 5.73.0 Qt Version: 5.15.0 Kernel Version: 5.3.0-51-generic OS Type: 64-bit Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz Memory: 7.7 GiB of RAM Graphics Processor: Mesa Intel® UHD Graphics 620
Nowadays, in KDE Plasma Version 5.22.5, I don't see such tearing caused by V-sync breaking, so it's time to close this ticket.