HDR + Wayland + Nvidia - Black Screen on Login

Hi all, been using KDE Plasma 6 on Wayland. I have a system with an Nvidia GPU. Previously, I had issues even logging into the system with a higher-than-60Hz refresh rate, seen here:

A fix was found - if not permanent, at least a solid temporary one:

Everything’s been working fine since…unless I enable HDR.

At first, I didn’t realize there was even a problem - I enabled HDR, tried to watch some HDR content, then had to depart the house. I had left my system on. On returning, I came back to my two non-HDR side monitors lit, but no response from mouse/keyboard, and my main (HDR) monitor not lighting up - it remained dark.

I used the “REISUB” method and rebooted, thankfully that worked. On reboot, it showed the login screen - on login…black screen, just like before.

Everything had been working fine for weeks until I enabled HDR. I did some digging, and found this:

I was able to log in to an X11 session, and followed the instructions in that thread to edit $HOME/.config/kwinoutputconfig.json and disable HDR for my display. I saw in that thread that the OP found the settings wouldn’t stick after a reboot.

So, I tried a log out and log in (to a Wayland session) - no dice, got the black screen.

I rebooted, got back in X11, and used the solution in the thread - edit the file, then make it immutable, then reboot.

It worked! I then disabled the immutability of that file, enabled HDR, and then disabled it. Then I rebooted.

All good now. So why the thread? Because the problem isn’t solved of course - can’t use HDR on KDE Plasma 6 Wayland, at least with an Nvidia GPU.

Does anyone know of a permanent fix to make this work? Or will the “explicit sync” update in the future possibly fix all this?

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Damn, guess nobody else having this problem, or nobody else knows the solution?

I’m not sure if wayland even supports HDR. But with nvidia on wayland you were always gonna be fighting an uphill battle.


Wayland on Plasma 6 added HDR - it’s not on X11. Here’s the settings, for example:

Well, it is experimental support, maybe just doesn’t work with nvidia. You may wanna try asking around in the kde community, you’re likelier to find answers there, using nvidia on wayland is already a niche thing, most people avoid it. using nvidia and using hdr on wayland at the sametime? I don’t think there are many at all, but if there are you’re likelier to find them there than here I’m afraid.

Hmm, I’ll check out KDE community then yeah.

That said, recently The Linux Experiment did a video on what GPUs people use - not super-scientific, but IIRC Nvidia came out on top, and KDE had a very big showing as well. I think the increase in gaming on Linux has been a driver for that (it’s what pushed me to Linux - now I use Windows only for the few games which I can’t run in ideal fashion on Linux).

That makes sense yeah, but did it define if it was kde wayland or kde x11 they were using?

To my recollection it was X11 or not mentioned - I think Wayland is still just too new for mass adoption.

Operating a bit off memory here so I might be wrong, haha.

Another big one is the merging of initial HDR support for gaming (which I previously reported on), that has also now been accepted, using a cut-down version of the upstream protocol that isn’t yet finished so that the Plasma team can let people test and play with the HDR implementation for gaming.


In the Plasma Wayland session, there’s now preliminary support for playing HDR-capable games when using an HDR-capable screen! (Xaver Hugl, link)

Looks still a bit like WIP, and we all know even Wayland support in general on Plasma 6 is still causing some issues all over the place.

Oh OK, I didn’t realize just how preliminary. Guess I will sit tight, haha. Thanks!