[openchrome-users] screen rotation

[peter]

hello.
is there any way to enable the screen rotation with the openchrome driver and an vx900 chipset?
randr is complaining: configure crtc 0 failed
adding option Rotate or ShadowFB in xorg.conf freezes the whole system when starting x.
while adding the option RotationType SWRandR,  x starts but randr is still complaining.
i'm running linux mint 20, beside the message "[drm] Failed to open DRM device for
pci:0000:00:01.0: No such file or directory" the driver seems to work fine.

thanks in advance
peter