In Plasma6.1, if I enable HDR on my monitor and enable HDR in Plasma6.1, next time I reboot the computer, the monitor still stays in HDR mode.
In Plasma6.2, even if HDR is enabled in Plasma 6.2, my monitor falls back to non-HDR mode when I reboot, and I have to enable it every time. It also happens if I turn off the monitor and turn it back on.
Log out then log in again also triggers this issue.
It must be a kwin bug, because even the experimental HDR in Gnome does not have this issue.
In fact, I did report a similar issue for Plasma6.1 long time ago in the drm bug report, but nobody replied, and KDE developers thought it was a drm bug, if it was a drm bug, how could it only happen to KDE but not Gnome?
I’m having a similar issue in 6.2.0 and 6.2.1 where one of my monitors switches out of HDR mode whenever I adjust my brightness. I actually have two HDR monitors though (a gigabyte and acer monitor), and the gigabyte one that lets me force HDR on is unaffected. My acer monitor will only allow me to set HDR to “auto”, and I have to manually switch the monitor back to this every time I adjust my brightness.
I can see the same brightness issue, too.
My monitor is Acer XV275K P3.
In fact, with Plasma 6.0, there already was the HDR issue when I locked my screen, after I woke up my screen, it left HDR mode, it doesn’t happen to Gnome experimental HDR either.
No, that’s not how anything works. The problem doesn’t happen on my PC, but I don’t accuse your specific PC being the problem when you report the bug that it’s broken on yours.
There’s no thinking involved, drm_info doesn’t lie. If the kernel says the display is in HDR mode, but it isn’t, there’s only the monitor or the GPU driver that can be broken.
It happens all the time that driver bugs happen only with some specific timing, only if you use some specific API, or only if you use some APIs in combination.
Are you adjusting the brightness on the monitor itself, or with the brightness slider in Plasma? Tons of monitors have weird quirks when it comes to brightness and HDR, if you do things on it directly, I wouldn’t be surprised if that causes issues.
If you see this happening when you adjust the brightness sliders in Plasma, please make a bug report about it, with the drm_info output before and after triggering the issue.
I’m using the brightness slider in plasma- the monitor OSD doesn’t have brightness controls with HDR enabled (until it gets bumped back to SDR after adjusting the brightness in plasma).
Okay, then please make that bug report for KWin, with the drm_info output. The output of kscreen-doctor -o before and after triggering the issue could also help.