https://bugs.kde.org/show_bug.cgi?id=500258
Bug ID: 500258
Summary: [Wayland] Screen does not wake up
Classification: Plasma
Product: plasmashell
Version: 6.3.0
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Power management & brightness
Assignee: plasma-b...@kde.org
Reporter: abaris...@gmail.com
Target Milestone: 1.0
SUMMARY
I have a 4k 144hz screen (LG 27GR95UM-B) hooked up to a NVidia 4080. I run KDE
using wayland and Nvidia's 570 drivers. The screen supports VRR and uses DSC
(display stream compression) to achieve more than 4k 120hz.
DSC is important here as I've experienced a lot of bugs both on Windows & Linux
because of it, and I believe it's the culprit here.
My problem is that when I turn the display off and back on, be it immediatly or
after a long time, the output stays black. The session doesn't crash or
anything, it just doesn't render and the screen doesn't see any signal.
The only reliable way to get it back is to switch to another graphical desktop
(Ctrl Alt F2 on my current install, which is SDDM's Xorg session), wait for the
cursor to come up and then Ctrl Alt F1 back to KDE. It then comes back
immediatly.
Switching to a TTY then does NOT work, only switching to one _before_ I turn
the screen off does. Once I run into the bug, only the other graphical session
will do the trick.
This works as expected when using Gnome, X11 KDE or when I'm on a TTY (DSC
might be off on a TTY though).
WORKAROUND
Turning DCC or VRR off doesn't do anything. However, I noticed that going to a
lower resolution or refresh rate fixes the issue, which led me to Display
stream compression. Disabling DSC on the monitor fixes the issue (while
limiting me to 4k120).
STEPS TO REPRODUCE
1. Get a KDE Install, Wayland + Nvidia (open/closed driver does not matter) and
a screen using DSC (8k@60 or 4k@144)
2. Turn the screen off, wait until the "unplug" sound
3. Turn the screen back on
OBSERVED RESULT
The screen is black
EXPECTED RESULT
The screen should show what I left it on (desktop or lockscreen)
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.13.2-arch1 (latest archlinux)
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
ADDITIONAL INFORMATION
I also reproduce this on Fedora 41: I couldn't test X11 there as they disabled
X on the plasma spin.
I can't find anything of use in journalctl or dmesg: it's the same logs whether
I have DSC on or off. I'd gladly give more logs if someone has something they
want me to try/some place to look/some verbose logs to enable.
This has been happening for a while now, I'm not even sure when it started but
it was there on plasma 6.2 too.
Sorry if this is a duplicate. The bug looks like some reports I've seen on
forums or here, but it's always a bit different.
The closest I could find is https://bugs.kde.org/show_bug.cgi?id=453557 but I
run a single screen setup.
I also found threads about Samsung screens, so I tried to disable the
brightness management/etc and it didn't change anything.
Thanks for your time,
Arnaud
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