Bug 453930

Summary:	Scaling is off with dual displays when the vertical resolution is different
Product:	[Plasma] KScreen	Reporter:	Mario <mcamou>
Component:	common	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	nate
Priority:	NOR
Version First Reported In:	5.24.5
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Mario 2022-05-17 10:52:32 UTC

SUMMARY

Scaling is messed up on dual displays when the vertical resolution is different. I am using the proprietary  drivers (this is the scenario I tested, I'm not sure if it happens on other configurations). See the videos at https://drive.google.com/drive/folders/10OBUr5NXY7KI1olIfcxr93bRQAGpJcR- 

First video: The external monitor starts up at 3840x1080 (which matches the vertical resolution of the laptop monitor). Setting it to the proper 5120x1440 results in scaling being completely off (contents of the laptop screen spill over to the external monitor, and the bottom panel is off of the screen). Dragging the mouse shows that the pointer coordinates are shifted down/right from where the pointer is.

Second video: Same thing, but also setting the external monitor to be Primary. In this case the scaling works correctly.

Third video: I did not press Keep after setting the external monitor as Primary, so the configuration reverted. Now we have the opposite scaling problem: the bottom of the screen is black and pointer coordinates are shifted up/left.

OBSERVED RESULT

Scaling is completely off when the primary monitor has a lower vertical resolution than the secondary monitor

EXPECTED RESULT

Scaling should work correctly

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:  Manjaro Plasma Daily 202205150340

Comment 1 Nate Graham 2022-05-17 15:32:44 UTC

Are you using the Wayland session or the X11 session?

If you're using X11, can you try the Wayland session and see if it works there?

Comment 2 Mario 2022-05-17 16:40:10 UTC

OK, here's the deal. I found this issue while verifying that https://bugs.kde.org/show_bug.cgi?id=452397 was solved. However, at that time I didn't realize that the Manjaro Plasma Daily live CD was booting to X11, not Wayland.

I found this error using the Manjaro Plasma Daily 202205150340 Live CD. However, it is not occurring on my normal session (Kubuntu 21.10) which is ALSO using X11.

Trying Wayland on Kubuntu, I run against https://bugs.kde.org/show_bug.cgi?id=452397, which precludes testing for this specific bug. And I haven't found a live CD with daily builds that will allow me to boot into Wayland using the proprietary Nvidia drivers. I also tried compiling my own KDE but ran into dependency Hell even using `kdesrc-build`.

If you have a suggestion for how to do that I would really appreciate it, so that I can both validate https://bugs.kde.org/show_bug.cgi?id=452397 and verify this one.

Comment 3 Nate Graham 2022-05-18 16:52:22 UTC

You can ask for kelp using kdesrc-build in the kde-devel room on Matrix. But that shouldn't be necessary. Unstable/Testing/daily/git/CI/master builds provided by your distro of choice should provide the same thing.

Comment 4 Bug Janitor Service 2022-06-02 04:35:45 UTC

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

Comment 5 Bug Janitor Service 2022-06-17 04:35:30 UTC

This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!