I just got my new Raspberry Pi 4 and I'm trying to rotate the screen. Usually on previous Raspberry versions I did that simply by putting display_rotate=1 to config.txt, but when doing this on Raspberry 4 the screen is partly black and it's not rotated properly. Any ideas? Thanks in advance.
On the Raspberry Pi 4, the screen rotation is (finally !) handled via RandR:
DISPLAY=:0 xrandr --output HDMI1 --rotate left DISPLAY=:0 xrandr --output HDMI1 --rotate inverted DISPLAY=:0 xrandr --output HDMI1 --rotate normal
There is a workaround. When I ran into the same issue with the blackbox, I tried using xrandr but kept getting the error "can't open display". After some searching I found that if you're using the VC4 FKMS V3D driver (this is the default on the Raspberry Pi 4), then 90 and 270 degree rotations are not supported. So I commented out the "dtoverlay=vc4-kms-v3d" in /boot/config.txt and now I get the full screen in portait mode. Guess this is not the proper way, but it seems to work.