SUMMARY When my monitors sleep the panel notification for displaying brightness is changed. It goes from three monitors to two and I have to change the primary monitor manually. The device disappearing is Dell Inc. DELL S3422DWG and the remaining two monitors are Hewlett Packard HP 25es. STEPS TO REPRODUCE 1. Have all three monitors available to adjust brightness 2. Let monitors sleep 3. Have only two monitors available on wake OBSERVED RESULT Only 2/3 monitors are adjustable EXPECTED RESULT It should stay the same as before it slept and allow 3/3 monitors brightness to be adjusted KDE Plasma Version: 6.2.3 KDE Frameworks Version: 6.8.0 Qt Version: 6.8.0 Kernel Version: 6.12.1-arch1-1 (64-bit) Graphics Platform: Wayland Processors: 16 × AMD Ryzen 7 5800X3D 8-Core Processor Memory: 125.7 GiB of RAM Graphics Processor: AMD Radeon RX 6800 XT ADDITIONAL INFORMATION
Can you clarify what exactly happens on wake-up? - One of the monitors is black, but you can move the cursor onto it and see it, and drag windows onto it - One of the monitors is black, and you can move the cursor and windows onto it, but they disappear - One of the monitors is black, but you can't move the cursor or windows onto it - One of the monitors can't have its brightness changed using the Brightness and Color widget in the system tray - Something else - Some combination of these
Created attachment 176118 [details] brightness options I've added an image for the area where the issue is happening. Sorry no backtrace. You can see from my screenshot this is after the monitors wake from sleep. Before sleep it showed three monitors. So I can no longer change the brightness on my primary after wake as its removed from the list. There is no flickering of blacking of the screen unless you consider sleeping but there is no bug there.
You'll want to see the summary if you missed it because I left a detail out of the steps. 4. After wake less monitors are available in the brightness controls from the task panel. Hope that helps it was not an issue before 6.2.3
Thanks for confirming.
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.
Thank you I've subscribed and will update the status. *** This bug has been marked as a duplicate of bug 482713 ***