LCD backlight IOCTL

Hi, I'm searching for how we can specify the LCD backlight level through
/dev/fb.

And for this, should we introduce a new IOCTL?

 

FBIOGET/SET_BACKLIGHT

 

I looked through CONFIG_FB_BACKLIGHT and bl_dev registration but I found
this is more of internal usage when there is fb event and I don't really
see how user app can specify the level.