Created attachment 182377 [details] Showcase of the brightness mismatch. SUMMARY When trying to set the monitor brightness to 57% (Without DDC/CI), it changes it to 56% after applying the change. STEPS TO REPRODUCE 1. Under System Settings -> Display Configuration, disable "Control hardware brightness with DDC/CI". 2. Set brightness to 57% in either system settings, or by using the Brightness & Colour Applet. OBSERVED RESULT The brightness under System Settings -> Display Configuration will be set to 56%, but the Brightness & Colour Applet shows 57%. EXPECTED RESULT It should display 57% under System Settings -> Display Configuration. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora Linux 42 KDE Plasma Version: 6.4.0 KDE Frameworks Version: 6.15.0 Qt Version: 6.9.1 ADDITIONAL INFORMATION - Entering a value manually under System Settings -> Display Configuration -> Brightness is also buggy. It either doesn't work sometimes, or it switches up the "%" symbol around.
Created attachment 182378 [details] Showcase of the manually entering value bug. The percentage symbol gets swapped around, and there doesn't seem to be a character limit.
I can reproduce this mismatch. Probably the two calculations round off the returned value in slightly different ways.
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kscreen/-/merge_requests/407
Git commit 414a6c7877cdcc3f26e679fedf98b43ea572613b by Xaver Hugl. Committed on 26/06/2025 at 12:20. Pushed by zamundaaa into branch 'master'. kcm: round brightness value Otherwise, slight floating point differences can change the value M +2 -2 kcm/ui/OutputPanel.qml https://invent.kde.org/plasma/kscreen/-/commit/414a6c7877cdcc3f26e679fedf98b43ea572613b
Git commit 0a9f419957252c93e9f7a73622086ad9441e1b57 by Xaver Hugl, on behalf of Xaver Hugl. Committed on 26/06/2025 at 15:56. Pushed by zamundaaa into branch 'Plasma/6.4'. kcm: round brightness value Otherwise, slight floating point differences can change the value (cherry picked from commit 414a6c7877cdcc3f26e679fedf98b43ea572613b) Co-authored-by: Xaver Hugl <xaver.hugl@kde.org> M +2 -2 kcm/ui/OutputPanel.qml https://invent.kde.org/plasma/kscreen/-/commit/0a9f419957252c93e9f7a73622086ad9441e1b57
Git commit ecc9f70d857fcbc651a090905b54731855172049 by Xaver Hugl, on behalf of Xaver Hugl. Committed on 26/06/2025 at 15:57. Pushed by zamundaaa into branch 'Plasma/6.3'. kcm: round brightness value Otherwise, slight floating point differences can change the value (cherry picked from commit 414a6c7877cdcc3f26e679fedf98b43ea572613b) Co-authored-by: Xaver Hugl <xaver.hugl@kde.org> M +2 -2 kcm/ui/OutputPanel.qml https://invent.kde.org/plasma/kscreen/-/commit/ecc9f70d857fcbc651a090905b54731855172049