Bug 438833

Summary:	Everything jerks when changing laptop brightness and external screen is enabled
Product:	[Plasma] kwin	Reporter:	sedrubal <kde>
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	kde, nate, xaver.hugl
Priority:	NOR
Version First Reported In:	5.18.1
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description sedrubal 2021-06-17 22:30:33 UTC

SUMMARY
When I plug in an external monitor and change my laptop display brightness or lock my screen, everything (graphics, music, cursor) jerks for about one minute and then it works again.

STEPS TO REPRODUCE
0. Use plasma desktop with X11
1. Plug in an external monitor
2. Extend screen to that monitor
3. Change display brightness or lock screen

OBSERVED RESULT
Everything jerks and CPU fan turns up for about one minute. Then everything works again.

EXPECTED RESULT
Graphics and music should stay fluent.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 5.22.1
KDE Frameworks Version: 5.83.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Kernel 5.10.44
Graphics Platform: X11

in journal this lines are showing up multiple times in that time span:

kscreen_backend_launcher[1033]: kscreen.xcb.helper:         State (newValue, Deleted):  0
kscreen_backend_launcher[1033]: kscreen.xcb.helper:         Property:  BACKLIGHT
kscreen_backend_launcher[1033]: kscreen.xcb.helper:         Output:  67
kscreen_backend_launcher[1033]: kscreen.xcb.helper: RRNotify_OutputProperty (ignored)

Comment 1 sedrubal 2021-06-25 08:10:27 UTC

To add some more info:
Sometimes jerking does not end but can be resolved, when I active my internal laptop display additionally to an external screen, that is already activated. Actually I want to switch to the second screen and disable the laptop screen. This is the output of `kscreen-doctor --outputs --info`

Environment:
  * KSCREEN_BACKEND           : [not set]
  * KSCREEN_BACKEND_INPROCESS : [not set]
  * KSCREEN_LOGGING           : [not set]
Logging to                : [logging disabled]
Preferred KScreen backend : KSC_XRandR.so
Available KScreen backends:
  * KSC_Fake.so: /usr/lib/qt/plugins/kf5/kscreen/KSC_Fake.so
  * KSC_KWayland.so: /usr/lib/qt/plugins/kf5/kscreen/KSC_KWayland.so
  * KSC_QScreen.so: /usr/lib/qt/plugins/kf5/kscreen/KSC_QScreen.so
  * KSC_XRandR.so: /usr/lib/qt/plugins/kf5/kscreen/KSC_XRandR.so
  * KSC_XRandR11.so: /usr/lib/qt/plugins/kf5/kscreen/KSC_XRandR11.so

Output: 67 eDP1 enabled connected  Panel Modes: 504:1920x1080@60 505:1680x1050@60 506:1400x1050@60 507:1600x900@60 508:1600x900@60 509:1600x900@60 510:1280x1024@60 511:1400x900@60 512:1400x900@60 513:1280x960@60 514:1368x768@60 515:1368x768@60 516:1368x768@60 517:1280x800@60 518:1280x800@60 519:1280x720@60 520:1280x720@60 521:1280x720@60 522:1024x768@60 523:1024x576@60 524:1024x576@60 525:1024x576@60 526:960x540@60 527:960x540@60 528:960x540@60 529:800x600@60 530:800x600@56 531:864x486@60 532:864x486@60 533:864x486@60 534:640x480@60 535:720x405@60 536:720x405@60 537:720x405@59 538:640x360@60 539:640x360@59 540:640x360@60 70:1920x1080@60*! Geometry: 0,1080 1920x1080 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable
Output: 68 VIRTUAL1 disabled disconnected  Unknown Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable
Output: 203 DP-1-1 disabled disconnected  DisplayPort Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable
Output: 204 DP-1-2 enabled connected primary DisplayPort Modes: 505:1680x1050@60 510:1280x1024@60 513:1280x960@60 522:1024x768@60 529:800x600@60 530:800x600@56 534:640x480@60 910:1920x1080@60*! 911:1920x1080@50 912:1920x1080@60 913:1920x1080@60 914:1920x1080@50 915:1920x1080@60 916:1280x1024@75 917:1440x900@60 918:1280x720@60 919:1280x720@50 920:1280x720@60 921:1024x768@75 922:1024x768@70 923:832x624@75 924:800x600@72 925:800x600@75 926:720x576@50 927:720x480@60 928:720x480@60 929:640x480@75 930:640x480@73 931:640x480@67 932:640x480@60 933:720x400@70 Geometry: 0,0 1920x1080 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable primary
Output: 205 DP-1-3 disabled disconnected  DisplayPort Modes: Geometry: 0,0 0x0 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable

Comment 2 Nate Graham 2022-11-08 22:06:48 UTC

Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Plasma 5.25 or 5.26?

If it is, please change the status to CONFIRMED when replying. If not, or if you can't because you no longer use this setup, you can change the status to RESOLVED WORKSFORME. Thanks a lot!