HDR + Wayland + Nvidia - Black Screen on Login

Desktop Environments Plasma
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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?

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

3

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

https://wiki.archlinux.org/title/HDR_monitor_support

4

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

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5

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.

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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).

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

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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.

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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.

Source:

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.

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