What: /sys/class/backlight//bl_power Date: April 2005 KernelVersion: 2.6.12 Contact: Richard Purdie Description: Control BACKLIGHT power, values are FB_BLANK_* from fb.h - FB_BLANK_UNBLANK (0) : power on. - FB_BLANK_POWERDOWN (4) : power off Users: HAL What: /sys/class/backlight//brightness Date: April 2005 KernelVersion: 2.6.12 Contact: Richard Purdie Description: Control the brightness for this . Values are between 0 and max_brightness. This file will also show the brightness level stored in the driver, which may not be the actual brightness (see actual_brightness). Users: HAL What: /sys/class/backlight//actual_brightness Date: March 2006 KernelVersion: 2.6.17 Contact: Richard Purdie Description: Show the actual brightness by querying the hardware. Users: HAL What: /sys/class/backlight//max_brightness Date: April 2005 KernelVersion: 2.6.12 Contact: Richard Purdie Description: Maximum brightness for . Users: HAL What: /sys/class/backlight//type Date: September 2010 KernelVersion: 2.6.37 Contact: Matthew Garrett Description: The type of interface controlled by . "firmware": The driver uses a standard firmware interface "platform": The driver uses a platform-specific interface "raw": The driver controls hardware registers directly In the general case, when multiple backlight interfaces are available for a single device, firmware control should be preferred to platform control should be preferred to raw control. Using a firmware interface reduces the probability of confusion with the hardware and the OS independently updating the backlight state. Platform interfaces are mostly a holdover from pre-standardisation of firmware interfaces.