https://bugs.kde.org/show_bug.cgi?id=448177
Bug ID: 448177
Summary: Thunderbolt dock 4k screen flickering
Product: kde
Version: unspecified
Platform: Gentoo Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: unassigned-b...@kde.org
Reporter: m...@qrly.wtf
Target Milestone: ---
Created attachment 145279
--> https://bugs.kde.org/attachment.cgi?id=145279&action=edit
Wird pixel rendering 4k@60Hz HDMI
Hello,
first, here is a short video showing the issue:
https://www.youtube.com/watch?v=c2sVZwb5mg0.
Basicly, I've got a 4k monitor connected on my Thinkpad thunderbolt 3 gen 2
Workstation dock:
Monitor: https://www.lg.com/us/monitors/lg-32UK550-B-4k-uhd-led-monitor
Dock:
https://support.lenovo.com/rs/en/solutions/pd500333-thinkpad-thunderbolt-3-workstation-dock-gen-2-overview-and-service-parts
The screen goes black after "changing to many pixels", for example while
fullscreen web browsing, playing a fullscreen video, etc. This only happens
while the monitor is running at 4k. 2k and blow is not an Issue.
This isn't a fix (because I tried it):
- Disabling all other monitors
- Only plugging the monitor Cable into the Dock
- Using another Thunderbolt dock
- Using other 4k Screens
- Using diffrent cables that I know work
- Using Manjaro KDE, KDE neon, endeavouros KDE, all showing the same behavior
How do I know that this is a Plasma specific issue?
Because the screen is working in Xfce and swaywm at 4k@60Hz.
It could also not be one, because same problem like in kde also exsists in dwm
and awesomewm.
Why do I use a docking station?
Because my Laptop (You can find my hardware specs below) only has 1.4b, which
after the official hdmi spec only supports 4k@30Hz (" 3840×2160 at 24, 25, and
30 Hz", https://www.hdmi.org/spec/hdmi1_4b) while my Displayport version
officially supports 4k@60Hz. My Laptop doesn't have a Displayport Port.
How do I know that this is a bug only appering when using a docking station?
I tried two diffrent docking stations, both showing the same result. (Maby I
will have the chance to test other laptops in the next days). While my HDMI
version doesn't officially supports 4k@60Hz, whith my HDMI port on my Laptop I
am able to achive 4k@60Hz, but with wird rendering(You can find a image showing
how the rendering looks in the attachments), thats why I need displayport.
But, 4k@60Hz on HDMI works without the wird black screen that you get when
"changing to many pixels".
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