Raspberry Pi 4 Problem with KDE Plasma screen flashes

I finally had enough when Gnome 40 came out, I switched to KDE PLASMA.
On the Raspberry Pi 4b KDE worked fine for about 9 or 10 weeks.

Then after an update, I have a problem with KDE PLASMA where every time I open or close a window, the screens goes totally black for about a second, then everything comes back to normal. Everything works but it sure is annoying.

It does this with the RPi 4b 4GB RAM, RPi 4b 8GB RAM, and the RPi 400.
This only does this on Arch Linux Arm / EndeavourOS on the KDE DE.
It does not happen on any other DE or WM that I know of. Although I haven’t tested all 10 of them recently.

I have tried different resolutions.

This happens with both the 32 Bit OS and the 64 Bit OS with KDE.
This happens on two different TVs and one Computer Monitor including a different HDMI cable each time.

I have turned the compositor off. No diff.

The funny thing is, I installed simple-screen-recorder (I think it was called) and recorded some activities involving opening and closing windows, and on the screen the symptoms appeared. I thought OK I have this problem captured. When the screen recording played back on VLC it looked perfect, no blanking screen. Go figure.

Logs:
https://clbin.com/kx0JM

Any help or guidance would be appreciated.

Pudge

think there setting speed up animations ( instant ) + change to fade when close (desktop effects). you look at this ? might be that .

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Thank you. :pray:
I have already been there and done that, was not the problem.

Pudge

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Sounds almost exactly like a problem I had on a Pi4B some weeks ago.
I assumed it was a quirk of my monitor, which worked ok with Raspberry Pi OS, but did the annoying blank-screen-on-window-change thing under EOS Arm 32/64bit.

From memory, I think I eventually resolved it by changing /boot/config.txt to explicitly specify values for hdmi_group, hdmi_mode and hdmi_drive, so the monitor would be detected as what the EDID said was preferred.

But I’ve just commented out those lines and rebooted, and the problem has not returned, which I cannot explain.

Nick

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Was that with KDE Plasma? I’ve not heard of this problem on anything but KDE.

Pudge

@n226

Excuse me, where are my manners. I forgot to welcome you to the EndeavourOS forum. SO:
WELCOME to the forum :beers:

I hope you enjoy your time here.

Pudge

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Yes it was. Also Cinnamon and LXQt.
Since I found this workaround, I’ve been using Cinnamon. I assume it would also work for KDE, but I haven’t tested.

And thank you for your welcome, and for your ARM scripts, which have been very useful.

Nick

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I’m having this problem with Xfce in an SD card. Tried changing the settings in /boot/config.txt

But what I tried didn't work.
disable_overscan=1
framebuffer_width=2560
framebuffer_height=1080
max_framebuffer_width=2560
max_framebuffer_height=1080
hdmi_group=2
hdmi_mode=87
hdmi_aspect_21_9=7
hdmi_cvt=2560 1080 60 7 0 0 1
hdmi_ignore_edid=0xa5000080
hdmi_pixel_freq_limit=400000000
hdmi_drive=2

From what I have seen, the RPi 4b devs are aware of this problem and are working on it.

In the meantime, here is a work around. Edit your
/boot/config.txt
file to the following. Make a backup of the existing config.txt, then:

# See /boot/overlays/README for all available options

dtoverlay=vc4-fkms-v3d
dtparam=i2c_arm=on
dtparam=spi=on
dtparam=audio=on
dtoverlay=w1-gpio
camera_auto_detect=1
display_auto_detect=1
initramfs initramfs-linux.img followkernel
disable_overscan=1
gpu_mem=512
max_framebuffers=2

[pi4]
# Run as fast as firmware / board allows
arm_boost=1

Note the first line is now
dtoverlay=vc4-fkms-v3d
f has been added in front of “kms”

If anyone tries this work around, let us know here if it fixes the black screen flashes or not.

Pudge

2 Likes