1What: /sys/class/backlight/<backlight>/bl_power 2Date: April 2005 3KernelVersion: 2.6.12 4Contact: Richard Purdie <rpurdie@rpsys.net> 5Description: 6 Control BACKLIGHT power, values are FB_BLANK_* from fb.h 7 - FB_BLANK_UNBLANK (0) : power on. 8 - FB_BLANK_POWERDOWN (4) : power off 9Users: HAL 10 11What: /sys/class/backlight/<backlight>/brightness 12Date: April 2005 13KernelVersion: 2.6.12 14Contact: Richard Purdie <rpurdie@rpsys.net> 15Description: 16 Control the brightness for this <backlight>. Values 17 are between 0 and max_brightness. This file will also 18 show the brightness level stored in the driver, which 19 may not be the actual brightness (see actual_brightness). 20Users: HAL 21 22What: /sys/class/backlight/<backlight>/actual_brightness 23Date: March 2006 24KernelVersion: 2.6.17 25Contact: Richard Purdie <rpurdie@rpsys.net> 26Description: 27 Show the actual brightness by querying the hardware. 28Users: HAL 29 30What: /sys/class/backlight/<backlight>/max_brightness 31Date: April 2005 32KernelVersion: 2.6.12 33Contact: Richard Purdie <rpurdie@rpsys.net> 34Description: 35 Maximum brightness for <backlight>. 36Users: HAL 37 38What: /sys/class/backlight/<backlight>/type 39Date: September 2010 40KernelVersion: 2.6.37 41Contact: Matthew Garrett <mjg@redhat.com> 42Description: 43 The type of interface controlled by <backlight>. 44 "firmware": The driver uses a standard firmware interface 45 "platform": The driver uses a platform-specific interface 46 "raw": The driver controls hardware registers directly 47 48 In the general case, when multiple backlight 49 interfaces are available for a single device, firmware 50 control should be preferred to platform control should 51 be preferred to raw control. Using a firmware 52 interface reduces the probability of confusion with 53 the hardware and the OS independently updating the 54 backlight state. Platform interfaces are mostly a 55 holdover from pre-standardisation of firmware 56 interfaces. 57