This chapter demonstrates how to rotate the screen in 90 degree increments using hardware acceleration. The VIA driver switches off the rotation option by default. To enable the rotation, add the following options in  Section "Device".

 Option    "Rotate"            "CW" (or "UD", "CCW")
 Option    "RotateType"    "HW" (or "SW")

The option "Rotate" specify the rotation degree, CW/UD/CCW stands for 90/180/270. The option "RotateType" decides the rotation process is done by the GPU hardware (HW) or the main CPU (SW). In Duo-view display mode, the rotation degree applies to both display devices, that is to rotate in the same direction, while in SAMM/DIH display mode two display devices can rotate in different directions.

If use hardware rotation, you should disable "Direct Frame Buffer" in BIOS settings, otherwise the display will be abnormal.