TS-4900 display rotation

Under Yocto you can use xrandr to rotate the screen:

export DISPLAY=:0 
xrandr --rotate left
xrandr --rotate right
xrandr --rotate normal
xrandr --rotate inverted

Under Debian or Ubuntu you can rotate the screen in the Xorg.conf. Edit the file /etc/X11/xorg.conf and append this to the end:

Section "Device"
    Identifier      "fbdev display"
    Driver          "fbdev"
    Option "Rotate" "CCW"
EndSection

After the display is rotated you will also need to rotate a touchscreen if this is being used. This example matches the CCW rotation, but swapaxes or the invertx/y options will need to be adjusted for other rotations.

Section "InputClass"
       Identifier "axis inversion"
       MatchIsTouchscreen "true"
       # swap x/y axes on the device. i.e. rotate by 90 degrees
       Option "SwapAxes" "on"
       # Invert the respective axis.
       Option "InvertX" "on"
       Option "InvertY" "off"
EndSection

On newer X11 releases libinput is used instead of the evdev driver. To rotate with Debian 10 and above this will require changing the coordinate transormation matrix. Edit /etc/X11/Xsession.d/10x11-ts-calibration and add the transformation matrix for your rotation to the end of the script. Eg, for clockwise rotations add:

xinput set-prop "ADS7846 Touchscreen" 'Coordinate Transformation Matrix' 0 -1 1 1 0 0 0 0 1