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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

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Wayland/X11 problems with 4K HDMI TV (discuss.tchncs.de)

submitted 5 months ago* (last edited 5 months ago) by [email protected] to c/[email protected]

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My current setup includes two 1440p monitors and a 4K TV . In the evening I use a script to switch off the monitors and use the TV. Due to the different resolutions, scaling is a problem. Both X11 and Wayland have their own problems.

My setup: Arch, KDE, Nvidia RTX 2060 with proprietary NVIDIA drivers (edit: version 545.29.06), 2x 1440p 144Hz monitors (DP-0, DP-1), 1x 4K 60Hz TV via (HDMI-0)

X11: Currently my procedure is as follows when I want to switch from monitors to my TV:

I turn the TV on
I change the Global scale to 175% via the KDE GUI. (I haven't found a command to implement in a script yet)
I use xrandr to switch to the TV only. xrandr --output HDMI-0 --primary --mode 3840x2160 --pos 5120x0 --rotate normal --rate 60 --output DP-0 --off --output DP-1 --off

The monitors turn off, but the TV shows a black screen. After a restart the TV works and the scaling is correct. So far I haven't found a way to change the scaling and switch to the TV without a restart.

Oddly if I turn on all screens at the same time, it works. All of them show the desktop xrandr --output HDMI-0 --mode 3840x2160 --pos 5120x0 --rotate normal --rate 60 --output DP-0 --primary --mode 2560x1440 --pos 0x1124 --rotate normal --output DP-1 --off --output DP-2 --mode 2560x1440 --pos 2560x1124 --rotate normal However, when I use step 3 afterwards, the TV shows a black screen again.

I tried to find solutions, but it's hard to figure out, since I'm not sure if it's a driver problem, KDE problem, ...

Wayland:

the max refresh rate for the TV is 30 Hz
with the TV turned on the system freezes every few seconds for a second or two

I haven't tinkered with Wayland a lot. The freezes make it a no-go for now. X11 at least has a workaround, even though it's a bit annoying.

Even though I have used Linux for a while. I'm probably still considered a beginner, so any help would be appreciated.

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[–] [email protected] 1 points 5 months ago* (last edited 5 months ago)

I'm on mobile so formatting might not look the best, but here it goes!

X11 scaling - does this link help? https://wiki.archlinux.org/title/HiDPI Specifically under either xorg or KDE plasma I think you might be able to find some settings that help

For Wayland - would wdisplays help you out? I've had good results using that along with kanshi.

As for system freezing, I'm just taking a shot in the dark but this might be a KDE thing based on a quick search. Wayland is new and sexy, but apparently all the bugs aren't worked out for KDE. This answer isn't great, and is very hand-wavey, but without more details outside of you're on KDE I can't really help much. Unfortunately for you, I switched over to Sway which apparently has better Wayland support out of the box.