Bug 468744

Summary:	Monitor show "No signal" in SDDM and KDE
Product:	[Plasma] kwin	Reporter:	Alexander Dyadyun <zlobniyshurik>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	nate, xaver.hugl, zlobniyshurik
Priority:	NOR
Version:	5.27.4
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Alexander Dyadyun 2023-04-21 03:48:21 UTC

Description of problem:
I have system with two monitors:
Main monitor - AOC275QXL (HDMI 2560x1440 FreeSync)
Auxiliary monitor - Nec2090 (DVI-D 1600x1200)
Video HD4550 (HDMI+DVI-D)
Just before start SDDM my AOC275QXL show "No signal".

How reproducible:
always

Steps to Reproduce:
1. Power on system - picture on both monitors
2. Select fedora in grub - picture on both monitors
3. View boot logs (rhgb disabled) - picture on both monitors
4. Start SDDM - picture only on auxiliary monitor

Actual results:
"No signal" on main monitor after SDDM start. In KDE for X11 and Wayland modes main monitor show "No signal".

Expected results:
Both monitors can show picture in SDDM & KDE

Additional info:
In "KDE monitor settings" I can see both monitors. I can change resolution for main monitor, turn on/off "Main monitor switch", enable/disable monitor - no visual changes on main monitor (still "No signal").

Start system only on main monitor got same effect - "No signal" after SDDM start

This configuration normally worked before on F37. During F38 install (from scratch) installer worked on main monitor without problems.

With x11 enabled in SDDM I have both monitors working.
Than, if I load KDE in x11 mode, both monitors working too!

But if I load KDE in wayland mode, my main monitor show "No signal". 
Re-enter in KDE after that in x11 mode did not help. Only system reboot enable main monitor again.

Initial bug report was in https://bugzilla.redhat.com/show_bug.cgi?id=2187036

Comment 1 Nate Graham 2023-04-21 14:27:10 UTC

Seems like a user-facing regression when using SDDM in native Wayland mode, which makes KWin the compositor for it. Moving the bug report to KWin.

Comment 2 Zamundaaa 2023-04-27 16:20:36 UTC

Please attach the output of drm_info (https://gitlab.freedesktop.org/emersion/drm_info) and the kwin log (journactl --user-unit plasma-kwin_wayland --boot 0) after reproducing the issue. The output of drm_info on X11 when it works and when it doesn't work to compare could be useful too

Comment 3 Alexander Dyadyun 2023-05-06 02:22:49 UTC

Sorry, can not reproduce this bug anymore. May be last updates fix this somehow.
Both modes (X11 & Wayland) work properly in SDDM and KDE now.