I have a original RPI-Touch-Display (the “old” one with 800x480 resolution) and i think since the move from kernel 6.1 to 6.6 the touchscreen is not working anymore.
If i go to “mouse and touch” settings in xfce i can not see any device.
Is something known about this problem?
Any hints for troubleshoot this problem?
Edit:
Controlling the backlight via “/sys/class/backlight/rpi_backlight/brightness” is also gone.
Edit2:
Ok, looks like the PoE-Fan does also not work after the update.
Edit3:
I setup my Pi4 from scratch and it works now! 
So it has something to do with the update from kernel 6.1.X to 6.6.74!
I observed two things:
- After the update from 6.1.x to 6.6.x PoE-Fan and TouchPad stopped to work. So it looks like something with /sys/class/ is not ok.
- After setup from scratch it took very long to boot into XFCE. I had to disable “dev-dri-renderD128.device” and “dev-dri-card0.device” as described here: Booting on Pi4 Mate - this now has a 1,5 minute delay - #31 by The_Raven