https://bugs.kde.org/show_bug.cgi?id=496676
--- Comment #5 from Jakob Petsovits <jpe...@petsovits.com> --- 6.2.0 to 6.2.2 were always showing brightness controls. If the PowerDevil service finds hardware brightness controls to be working (via DDC/CI) for a given monitor, the brightness slider would affect hardware brightness. If no hardware brightness controls were found to work, KWin would expose software brightness controls instead, which changes the actual color values of pixels sent to the display. DDC/CI is not 100% reliable and it also seems we have an issue somewhere that makes it less reliable still, which I haven't figured out yet. Some people would initially have hardware brightness controls working for them, set the hardware brightness to e.g. 50%, and at some point DDC/CI stops working within PowerDevil, perhaps after restarting your system. At that point, KWin would use the 50% brightness value as software brightness, which dimmed the display to only 50% (pixel color) of the 50% hardware brightness that was already set, so 25% composite brightness, which was way too low and also really confusing. 6.2.3 contained a patch that fixed this confusion, at the cost of removing brightness controls where DDC/CI was once working but now isn't: https://invent.kde.org/plasma/kwin/-/merge_requests/6670 I suspect that this change made your brightness slider disappear. You can remove the line > "allowSdrSoftwareBrightness": false in your .config/kwinoutputconfig.json for your monitor, and the brightness slider will return unless DDC/CI starts working again, then it will disappear again (to avoid the aforementioned double-dimming problem). This is at best a short-term workaround. The long-term solution would be to figure out why DDC/CI is unreliable for some monitors. There is a long-running Bug 482713 where we fixed some of the issues, if we figure out what other kinds of problems there are then that's where a fix will get announced. I suggest closing this bug and subscribing to the other one instead, unless you disagree with some parts of my hypothesis. -- You are receiving this mail because: You are watching all bug changes.
