Bug 472581

Summary:	External screen doesn't turn on until after login
Product:	[Applications] systemsettings	Reporter:	php4fan
Component:	kcm_sddm	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	aleixpol, kde, kde, nate, notmart
Priority:	NOR	Keywords:	multiscreen
Version First Reported In:	5.27.6
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description php4fan 2023-07-24 15:44:19 UTC

SUMMARY
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***

STEPS TO REPRODUCE
1. I have an external screen connected to my laptop and I have it configured so that the external screen is the only screen in use
2. shut down the OS
3. power on the computer and immediately close the lid.

OBSERVED RESULT
Nothing seems to happen, the external screen doesn't turn on, and doesn't get any signal.
So I open the lid and see that the login screen is actually showing up on the builtin screen.
Even if I unplug the screen and plug it back in, nothing changes.
Only if I log in (for which I needed to open the lid), then after logging in, the external screen turns on and the builtin one turns off

EXPECTED RESULT
From the very beginning, as long as the external screen is connected, the system should use the saved configuration, which is to only have the external screen, and therefore the login screen should show up there.

NOTE: this used to work as expected. Now I turned it on and this happened. I don't know whether it's something that happens randomly, or if it's a recent regression. I haven't retried several times, I have immediately come to report this.

Operating System: Manjaro Linux
KDE Plasma Version: 5.27.6
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10
Kernel Version: 6.1.38-1-MANJARO (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-1065G7 CPU @ 1.30GHz
Memory: 7.3 GiB of RAM
Graphics Processor: Mesa Intel® Iris® Plus Graphics
Manufacturer: LENOVO
Product Name: 81WE
System Version: IdeaPad 3 15IIL05

Comment 1 Nate Graham 2023-08-30 20:24:29 UTC

This is because on the SDDM login screen, SDDM doesn't have your screen information in it.

If you use Wayland and sync your settings in System Settings > Startup and Shutdown > Login Screen (SDDM) > Apply Plasma Settings, then it should work. If that doesn't work, then it *might* be because SDDM itself has be running in native Wayland mode to, which to my knowledge Manjaro doesn't do out of the box. But you can turn it on for yourself; see https://wiki.archlinux.org/title/SDDM#Running_under_Wayland.

Can you try doing these things?

Comment 2 php4fan 2023-08-30 20:51:59 UTC

It's X11, not Wayland

Comment 3 Nate Graham 2023-08-30 20:54:39 UTC

I know. I'm asking you to try Wayland using the instructions I provided, because what you want to do isn't supported on X11.

Comment 4 php4fan 2023-08-30 21:04:37 UTC

> I'm asking you to try Wayland

Oh ok, no sorry I don't think I'm going to try Wayland any time soon.

> because what you want to do isn't supported on X11.

That's impossible, it used to work, I've been using this configuration for ages on this machine and the one before this; before Manjaro I had OpenSUSE and before that Ubuntu.

And by the way, my settings are actually irrelevant. I mentioned that my settings match the physical configuration because that seemed to me one less excuse for it not working, but even if settings are not accessible or if I turn on my computer with a different physical configuration, ability to log in has priority over anything else. If there's only one screen available, the login screen should show up there. Or just show it on all available screens for good measure.

Comment 5 Nate Graham 2023-08-30 21:08:58 UTC

We've never supported this in KDE code on X11, so if it used to work for you, it's because SDDM happened to randomly support it purely by chance, not as a supported thing, and then that must have broken recently. In which case, it would be an SDDM bug.

Normally I'd recommend that you report it there, but in all realism, there is no development on SDDM on X11 anymore, so I would recommend trying Wayland again, and submitting bug reports for things that aren't working as you expect so we can fix those things.