Bug 477987

Summary: The refresh rate is half that of an external monitor. Plasma 6 Beta
Product: [Plasma] kwin Reporter: Jesús Marín Almansa <jesus>
Component: wayland-genericAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED DUPLICATE    
Severity: normal CC: kde, xaver.hugl
Priority: NOR Keywords: qt6
Version: 5.90.0   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed In:

Description Jesús Marín Almansa 2023-12-03 13:01:55 UTC 
SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***


STEPS TO REPRODUCE
1. Connect an external display.
2. Set the FPS to 60 or 50.

OBSERVED RESULT
On the external display you will have at most half of the selected FPS.

EXPECTED RESULT
Get the selected fps and not half of them.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux. Plasma 6 beta
(available in About System)
KDE Plasma Version: 5.90.0
KDE Frameworks Version: 5.246.0 
Qt Version: 6.6.1

ADDITIONAL INFORMATION
My computer uses two graphics cards, the nvidia graphics (GeForce GTX 1050 Mobile) and the intel integrated one. In KDE Plasma 5 this bug was fixed with the following flag in /etc/environment : KWIN_DRM_USE_MODIFIERS=0.

I've been looking at other similar bugs where they tried using these others:
KWIN_DRM_DISABLE_BUFFER_READABILITY_CHECKS=1.
KWIN_DRM_PREFER_COLOR_DEPTH=24
KWIN_DRM_NO_AMS=1
All unsuccessful.

I provide you with the qdbus information in case it is relevant: https://pastebin.com/raw/jM79m5yt

Best regards,
Jesus.
Comment 1 David Edmundson 2023-12-03 14:04:18 UTC 
>On the external display you will have at most half of the selected FPS.

How are you determining the FPS?
Comment 2 Jesús Marín Almansa 2023-12-03 15:09:18 UTC 
(In reply to David Edmundson from comment #1)
> >On the external display you will have at most half of the selected FPS.
> 
> How are you determining the FPS?

Hi, Thank you for responding so quickly!

I am measuring it from the website https://www.testufo.com/ .

I have tried from both chrome and firefox. Both using Wayland (not xwayland). When the ufo test window is on the main screen, it shows 60 fps, but when I put it on the external monitor, it always drops to half of the settings.

Best regards,
Jesus.
Comment 3 Zamundaaa 2023-12-05 11:42:13 UTC 

*** This bug has been marked as a duplicate of bug 452219 ***