Error when updating to 8.9

Troubleshooting
41

Uh, that’s weird!

Anyway sorry but I was wrong, your suggestion doesn’t work, if I add the

dtoverlay=RPi-backlight

then

echo 1 > /sys/class/backlight/rpi_backlight/bl_power

doesn’t give me the error but the display stay ON, doesn’t turn OFF. The command does nothing… :frowning:

42

I found in german RPi forum a post from 2017 (I know, it’s quite old) where they say, it doesn’t work when touch is disabled.

1 Like
43

Thanks! No the touch now is disabled, but before 8.9 I was using both touch and I was able to turn off the display.

44

Found the solution to turn on-off the display! :partying_face:

That is too stupid to be real…but… something is different in 8.9, in order to turn on/off the display, the path is different

from

/sys/class/backlight/rpi_backlight/bl_power

to

/sys/class/backlight/backlight/bl_power

I spent days to try to load different driver from vc4-kms-dpi, the old vc4-fkms-dpi etc… but all that was needed was just to change the path :sweat_smile:

45

but this has no real relation to our DietPi version. We don’t maintain in /sys/class/backlight/backlight/bl_power or /sys/class/backlight/rpi_backlight/bl_power. Probably some other apt packages (like kernel) got updated in parallel.

46

I know! But for some reason something has changed,

I suspect this is something related to the

raspberrypi-sys-mods

Package that has been updated. Or the kernel or eeprom as you said!