Most drivers use the fbtft backlight support to control backlight. This is enabled if there is a 'led' gpio present.
These drivers will have backlight power control exposed in the sysfs filesystem.
# Turn off backlight echo 1 | sudo tee /sys/class/backlight/*/bl_power # Turn on backlight echo 0 | sudo tee /sys/class/backlight/*/bl_power
Brightness is currently not supported (need a kernel PWM driver).
/etc/udev/rules.d/backlight-permissions.rules
SUBSYSTEM=="backlight",RUN+="/bin/chmod 666 /sys/class/backlight/%k/brightness /sys/class/backlight/%k/bl_power"
Wiring Pi can be used to dim the backlight.
sudo gpio mode 7 write # Turn Off LCD backlight sudo gpio write 7 0 # Turn On LCD backlight sudo gpio write 7 1