https://bugs.kde.org/show_bug.cgi?id=409763
Bug ID: 409763
Summary: Kwin does not correctly detect refresh rate of PRIME
monitor
Product: kwin
Version: 5.16.3
Platform: Archlinux Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-x11-standalone
Assignee: kwin-bugs-n...@kde.org
Reporter: aska...@hotmail.fr
Target Milestone: ---
Created attachment 121491
--> https://bugs.kde.org/attachment.cgi?id=121491&action=edit
Output of "qdbus org.kde.KWin /KWin supportInformation"
Hi,
I was doing some testing with refresh rates on KDE, and I found out that KWin
isn't running at the proper refresh rate on Nvidia when there is a PRIME
monitor involved.
My setup : Optimus laptop with a dual-GPU Intel+Nvidia configuration. The X
session is running directly on the Nvidia chip. I have 2 monitors :
- The 120Hz built-in screen of the laptop. It's hardwired to the Intel chip,
but exposed to Nvidia as a PRIME monitor.
- A 144Hz external monitor plugged directly into the Nvidia card.
I assume that Kwin should run at one of those 2 refresh rates (preferably the
highest one), but here is what happens instead :
When both monitors are active : the refresh rate is 72Hz
When only the PRIME monitor is active : the refresh rate is 60Hz
When only the external monitor is active : the refresh rate is 144Hz
(Note that I am using the "Show FPS" desktop effect to measure the framerate.
Since it's capped at 100 I can't be 100% sure that the monitor is really
running at 144Hz in the last case, but there is not a single doubt that the
framerate is much higher than in the 2 other cases).
I tried disabling PRIME Sync by disabling modesetting in the Nvidia driver, but
it made no difference. However, disabling the Nvidia card and running the
session on the Intel chip (which does not involve PRIME since the built-in
screen is directly connected) makes Kwin run at the correct framerate.
Finally, I found out that adding "MaxFPS=144" to the "[Compositing]" section of
~/.kwinrc fixes the issue. So it really looks like KWin fails to detect the
refresh rate of the PRIME monitor.
This seems to be confirmed by running "qdbus org.kde.KWin /KWin
supportInformation". It shows :
Screen 0:
---------
Name: DP-0
Geometry: 0,0,1920x1080
Scale: 1
Refresh Rate: 143.996
Screen 1:
---------
Name: eDP-1-1
Geometry: 1919,0,1920x1080
Scale: 1
Refresh Rate: 60.0078
And, you guessed it, that 60Hz on Screen 1 is not correct.
SOFTWARE/OS VERSIONS
Archlinux
Kernel 5.1.16
Plasma 5.16.3
KDE Frameworks 5.59.0
Qt 5.13.0
--
You are receiving this mail because:
You are watching all bug changes.
