Bug 511130

Summary:	KDE doesn't work with custom EDID virtual displays
Product:	[Plasma] KScreen	Reporter:	Adam <adam>
Component:	common	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	REPORTED ---
Severity:	normal	CC:	nate
Priority:	NOR
Version First Reported In:	6.5.0
Target Milestone:	---
Platform:	Other
OS:	Linux
See Also:	https://bugs.kde.org/show_bug.cgi?id=481584
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	No display shows with this EDID. No display showed with this EDID. This EDID worked perfectly fine. Only the standard and established timings worked with this EDID (prefered resolution of 2160x1620 wasn't available) Only the standard and established timings worked with this EDID (prefered resolution of 2160x1620 wasn't available) No display showed with this EDID.

Description Adam 2025-10-26 00:17:22 UTC

Created attachment 186161 [details]
No display shows with this EDID.

SUMMARY
Attempted to use an iPad 9th gen as a second monitor with the following software:
Arch Linux
KDE Plasma 6.5.0 (Wayland)
Sunshine (Server)
Moonlight (Client)
Virtual Display
 - Tried with krfb-virtualmonitor and custom EDID w/ Kernel parameters and modified initramfs

I was successful in getting this to work, but wasn't able to set the virtual monitor to any non-standard resolution or any resolution above 1080p (iPad 9th gen is 2160x1620@60 and 4:3). I tried with multiple EDIDs, including custom generated ones through Linux tools (cvt, edid-generator, edid-decode, etc) and online tools like edidcraft.com as well as modified ones exported from Custom Resolution Utility (CRU) on Windows. I have a laptop with a 4:3 2880x1800@60 display and tried this resolution as well as modifying it to 2160x1620@60. No resolutions above 1080p showed in kscreeen-doctor or KDE settings.

STEPS TO REPRODUCE
1. Followed this guide: https://www.azdanov.dev/articles/2025/how-to-create-a-virtual-display-for-sunshine-on-arch-linux
2. 
3. 

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: 
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

Comment 1 Adam 2025-10-26 00:19:08 UTC

Created attachment 186162 [details]
No display showed with this EDID.

Comment 2 Adam 2025-10-26 00:19:47 UTC

Created attachment 186163 [details]
This EDID worked perfectly fine.

Comment 3 Adam 2025-10-26 00:21:13 UTC

Created attachment 186164 [details]
Only the standard and established timings worked with this EDID (prefered resolution of 2160x1620 wasn't available)

Comment 4 Adam 2025-10-26 00:21:47 UTC

Created attachment 186165 [details]
Only the standard and established timings worked with this EDID (prefered resolution of 2160x1620 wasn't available)

Comment 5 Adam 2025-10-26 00:22:23 UTC

Created attachment 186166 [details]
No display showed with this EDID.

Comment 6 Adam 2025-10-26 00:32:35 UTC

*Bug report posted when I pressed enter when adding a description to one of the attachments. I can't seem to be able to edit the original report, so I'll finish it here.*

STEPS TO REPRODUCE
1. Followed this guide: https://www.azdanov.dev/articles/2025/how-to-create-a-virtual-display-for-sunshine-on-arch-linux
2. Repeated with all EDID binaries in attached.
3. Attempted different variations of kernel parameters following the Arch Wiki: https://wiki.archlinux.org/title/Kernel_mode_setting#Forcing_modes_and_EDID

OBSERVED RESULT
Only standard resolutions up to 1920x1080 were available for the virtual monitor. Everything above this was ignored without regard to timings, refresh rate, or seemingly any other parameters. If the EDID exposed a standardized resolution at or below 1920x1080@60, it showed as available on the system. Otherwise, it was completely ignored. This issue does not seem to be present on other DEs at the moment and seems unique to KWin/Kscreen.

EXPECTED RESULT
All valid resolutions/timings present in the EDID should be available through kscreen-doctor and KDE Plasma Settings.

SOFTWARE/OS VERSIONS
Arch Linux: 6.17.5-arch1-1
KDE Plasma Version: 6.5.0
KDE Frameworks Version: 5.19.0
Qt Version: 6.10.0

Comment 7 Adam 2025-10-27 19:02:44 UTC

Update: I attempted the same set of steps to add and force non-standard resolutions after obtaining and using an HDMI dummy plug. No non-standard resolutions worked through either EDID override or setting the resolution directly in the kernel parameters.