Bug 494878

Summary:	KWin 6.2.1 breaks rotation of display and mouse cursor
Product:	[Plasma] kwin	Reporter:	betaminos
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	privat
Priority:	NOR
Version First Reported In:	6.2.1
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description betaminos 2024-10-16 17:43:19 UTC

SUMMARY
Upon updating kwin from 6.2.0 to 6.2.1 and rebooting, my desktop (usually rotated by 90°) will only show half of the screen with the other half black.
My mouse cursor was not visible, with interactions (e.g. right click or pressing the windows-key) causing the working half of the screen to flicker and partially update. 

STEPS TO REPRODUCE
1. Install Plasma 6.2.0
2. Apply rotation of screen (90°)
3. Update to Plasma 6.2.1
4. Reboot

OBSERVED RESULT
Rotated screen is only displaying one half (90° causes the left side of the screen to show), mouse cursor is invisble

EXPECTED RESULT
Rotated screen and mouse cursor showing as per usual

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux (CachyOs) 
KDE Plasma Version: 6.2.1
KDE Frameworks Version: 6.7.0
Qt Version: 6.8.0

ADDITIONAL INFORMATION
Forcibly downgrading kwin (and only kwin) to version 6.2.0 sitting in my pacman cache and rebooting works around the issue.
Deleting the cached packages of kwin version 6.2.1 and redownloading them results in the same issue - as does redownloading after switching mirrors.

Removing the screen rotation (= 0°) gets rid of only half the screen rendering, but the mouse cursor remains missing.
Strangely enough, if I shake the mouse (causing it to grow for easier finding) it will show up in the 0°-rotation for as long as it is larger than usual.

Comment 1 betaminos 2024-10-16 17:50:35 UTC

I have found a report of a similar sounding issue here: https://www.reddit.com/r/kde/comments/1g4ntqr/621_update_broke_cursor_behaviour/
There is a bug mentioned in the thread above: https://bugs.kde.org/show_bug.cgi?id=494829

Comment 2 betaminos 2024-10-16 17:57:16 UTC

Sorry, I am just realizing that I have missed adding my system details:
CPU: Intel i7 1165g7 (includes the Intel Xe GPU)
RAM: 16GB
Graphics Platform: Wayland

The issue happens regardless of using mesa-git (from AUR) or the current stable mesa, and it shows up with the LTS kernel as well as 6.11.3-3-cachyos.

Comment 3 Peter Kreussel 2024-10-16 19:17:47 UTC

On my Arch System on updating from 6.2.0 to 6.2.1 on my screen set to rotated by 90° (i.e pivot position)  I see the following:
- the image on that screen is not rotated anymore,  but distorted to the pivot format without rotation
- only if I either turn the lightness down below 100% in the Lightness Applet or if Nightlight coloring is active.

I'm using the proprietory nvdidia driver 560.35.03. The malfunctioning rotated screen is on a HDMI connection, my primary screen on display port. I see this only on wayland, not X11.

The commit that breaks it for me is 72f1dd2a (upload custom geometry instead of using glScissor) according to my bisecting.

(Sorry if I'm wrong thinking that this might be the same bug...)

Comment 4 betaminos 2024-10-17 20:53:12 UTC

After updating to 6.2.1.1 the issue is gone: I am seeing my mouse cursor as well as the screen rotating correctly.
Thank you for the quick fix in the other ticket 👍