Split screen/display corruption issue on HP Envy 15-ep0004ns

With kernels 6.6.0 (driver 20200114) and newers, the laptop screen is squashed into the top half, making it unusable.

Kernel 5.5.13 (driver 20191101) works correctly (still some glitches each minute or so, but usable).

The behaviour looks the same as in 97822, but in this case the BIOS does not have config to disable boot legacy support.

I have captured some that with this script for kernels 5.5.13-arch2-1 and 5.5.13-arch2-1:

DIR=$(realpath $(uname -r))
mkdir -p $DIR/{dri,drm}
sudo rsync -a --exclude "data" /sys/kernel/debug/dri/0/ $DIR/dri/
sudo chown -R adrian $DIR
cd $DIR/dri ; find . -type f -exec bash -c "sudo cp /sys/kernel/debug/dri/0/{} ." \;
sudo cp -r --copy-contents /sys/class/drm/card0/ $DIR/drm
sudo dmesg > $DIR/dmesg
sudo dmesg --level=err > $DIR/dmesg.err

I have also found that reading the file /sys/kernel/debug/dri/0/crtc-0/crc/data with cat in kernel 5.4.94 (the one I'm currently using), put the screen into the "half mode", sometimes temporarily vid

Sometimes permanent (just tried while writing this issue).

The lower half is sometimes black, sometimes white, sometimes with strange bars. Looks like it depends on what was on the screen.

I turned off the screen with xrandr and back on, but still only half screen. I was finally able to "recover" the screen cating again the file /sys/kernel/debug/dri/0/crtc-0/crc/data

Doing that cat in newer kernels does nothing (I was thinking maybe it fixed the screen, at least for a while).

Forgot to mention that I need to use older kernels toghether with xf86-video-intel to get an usable configuration. Older kernels without that driver blinks like each 2".