[SOLVED] Flickering & Blanking screen upon switching window

[jyno]

Screen gets blank upon window switch.
This differs from screen to screen (on some, the blackout is longer and on others it's shorter)

This occurs on Fluxbox, Openbox, and LXQt.
In a Kodi session, screen doesn't get blank.

As long as the current window is focused, screen is OK.
It happens when switching with GTK/KDE/Qt software.
This doesn't happen when switching from one Terminal Emulator to another one.

This problem began a week ago.
Reinstalling Xorg, DOES NOT fix this problem.

Notes:
Tried with different monitors.
Tried with different RPi4.

It happened also to another ArchLinuxARM installation, after running $this->bbcode_second_pass_code('', 'pacman -Syu')

[darksky]

I noticed this also with the latest 5.10.76 on my rpi with their code changes when using kms with v3d rendering. It does not seem to happen with fkms with v3d rendering.

Will have to wait for them to try to fix it using kms with v3d rendering. I temporarily reverted their commit.

https://github.com/raspberrypi/linux/issues/4660

[jyno]

Kudos!

It was important for me to get a confirmation that it's not specific to my installation.

Thank you

[darksky]

FYI: I compiled the new RPi 5.15.0 kernel this mourning and it does not have that issue.

[jyno]

It was OK after a while. Right now, it is present again.

Suspected package: $this->bbcode_second_pass_code('', 'linux-raspberrypi4-5.10.78-2')

[TrevorB]

I am having the same problem, when I did my first install about a week ago, all was okay for a couple of days until something seems to have broken it in the updates

Tried downgrading to 5.10.78-1 & 5.10.77-1 didn't change anything

Just did a clean install (for fun...) same problem

Running Pi4 Xfce, with lightdm as DE

[unformatted]

I'm having exact the same problem on RPi4 aarch64 using linux-raspberrypi4 5.10.78-2 kernel. I'm using LXDE.

[unformatted]

I just did a full upgrade (pacman -Syu) and am now running latest linux-raspberrypi4 5.10.79-2 kernel. Same issue.

[TrevorB]

Sadly, same here, updating all this morning, same problem

Update/ edit : Reading Darksky's post below and reading the the link he posted

I modified by /boot/config/txt

from
dtoverlay=vc4-kms-v3d
to
dtoverlay=vc4-fkms-v3d

saved the file and rebooted, Flickering screen has gone

Now I only 'play' with this Pi4 so don't really use it much except for trying to learn more about Linux

For the moment it solves the problem so I'll stay with that modif until it gets worked out

[darksky]

I told them about it yesterday. It is happening again with the latest 5.15.2 at 46c99e3 and the latest 5.10.79 at 027a7a8 kernels. I posted it at the bottom of same original issue thread when it first started.

https://github.com/raspberrypi/linux/issues/4660