In this post, we shows how to rotate the screen in pcDuino (Ubuntu OS):

We can  add “Rotate” Option in /etc/X11/xorg.conf:

Section "Device"
        Identifier "Mali FBDEV"
        Driver  "mali"
        Driver  "fbdev"   ## This is what changed
        Option  "fbdev"            "/dev/fb0"
        Option  "DRI"             "false"
        Option  "DRI2"             "true"
        Option  "DRI2_PAGE_FLIP"   "true"
        Option  "DRI2_WAIT_VSYNC"  "false"
        Option "Debug" "true"
       Option  "Rotate"    "CW" ## This is what changed
EndSection

Save the change, and reboot pcDuino. We will observe the screen rotated!