I bought a simple display with HDMI but there is a manual switch for the backlight on it, instad of using a HSYNC with HDMI.
Now I see that the /lib/modules/4.9.35-v7+/kernel/drivers/video/backlight/gpio_backlight.ko driver module is available in standard raspbian image out of the box.
My question: I do not change the raspian device tree. How can I load the driver with giving it a GPIO number? Or do I have to change the tree first and then modprobe the driver?