Bug 448376

Summary: External monitor: graphical issues in Wayland after update to 5.23.90
Product: [Plasma] kwin Reporter: Linus Dierheimer <Linus>
Component: platform-wayland-nestedAssignee: Martin Flöser <mgraesslin>
Severity: major CC: kwin-bugs-null, Linus, nate, xaver.hugl
Priority: VHI Keywords: regression
Version: 5.23.90   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed In: 5.24
Attachments: Picture of the monitor
drm_info in 5.23.5, monitor looks normal
drm_info in 5.23.90 monitor looks weird
drm_info in 5.23.90 , with env var, monitor looks normal again

Description Linus Dierheimer 2022-01-13 17:44:05 UTC
Created attachment 145419 [details]
Picture of the monitor


After updating to the 5.24 Beta (5.23.90), my external monitor (HDMI) has major graphical issues. The colors look inverted and the lines are not sharp anymore. See the  attached picture. In a screenshot it looks normal. Happens only in the wayland session, X11 works perfectly fine. I tried all the color correction profiles that are now in the system settings, i were able to see a difference, but none of them fixed the problem.

1. Update your Arch system with the kde-unstable repositories to the latest version (Frameworks 5.90, Plasma 5.23.90)
2. Connect an external Monitor via HDMI
3. Look at it


Monitor has graphical glitches


Monitor looks fine

Windows: /
macOS:  /
Linux/KDE Plasma: 5.16.0 / 5.23.90
(available in About System)
KDE Plasma Version: 5.23.90
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2

Comment 1 Linus Dierheimer 2022-01-13 18:00:01 UTC
Tested it with Display Port, same problem. So not a HDMI fault but wayland in general.
Comment 2 Nate Graham 2022-01-13 21:43:20 UTC
Are you by any chance using an Intel Tiger lake series CPU and iGPU?
Comment 3 Linus Dierheimer 2022-01-13 21:47:32 UTC
No, Ryzen 7 4800H with an Radeon RX5600M graphics card (Dell G5 SE Laptop).
Comment 4 Nate Graham 2022-01-13 23:45:29 UTC
OK, thanks.
Comment 5 Zamundaaa 2022-01-14 00:00:26 UTC
You can try disabling deep color with the environment variable KWIN_DRM_PREFER_COLOR_DEPTH=24, maybe amdgpu has some issue with it.
Please also attach the output of drm_info (with default color depth)
Comment 6 Linus Dierheimer 2022-01-14 00:12:07 UTC
Created attachment 145434 [details]
drm_info in 5.23.5, monitor looks normal
Comment 7 Linus Dierheimer 2022-01-14 00:12:50 UTC
Created attachment 145435 [details]
drm_info in 5.23.90 monitor looks weird
Comment 8 Linus Dierheimer 2022-01-14 00:13:17 UTC
Created attachment 145436 [details]
drm_info in 5.23.90 , with env var, monitor looks normal again
Comment 9 Linus Dierheimer 2022-01-14 00:14:36 UTC
KWIN_DRM_PREFER_COLOR_DEPTH=24 did indeed fix the bug. Thank you very much! I added the requested drm_info outputs, if you need more info, feel free to ask.
Comment 10 Bug Janitor Service 2022-01-14 08:36:24 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/1877
Comment 11 Zamundaaa 2022-01-14 16:00:29 UTC
Git commit 0a3922e29dc937a0a14beed73266a4a9298a647a by Xaver Hugl.
Committed on 14/01/2022 at 15:44.
Pushed by zamundaaa into branch 'master'.

backends/drm: use the correct format for CPU copy

M  +1    -1    src/backends/drm/egl_gbm_backend.cpp

Comment 12 Zamundaaa 2022-01-14 16:02:29 UTC
Git commit c037e65d6894dcebf93b0cae6005010ac63541a8 by Xaver Hugl.
Committed on 14/01/2022 at 16:02.
Pushed by zamundaaa into branch 'Plasma/5.24'.

backends/drm: use the correct format for CPU copy

(cherry picked from commit 0a3922e29dc937a0a14beed73266a4a9298a647a)

M  +1    -1    src/backends/drm/egl_gbm_backend.cpp