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 compatible with 7 FB_BLANK_* from fb.h 8 9 - 0 (FB_BLANK_UNBLANK) : power on. 10 - 4 (FB_BLANK_POWERDOWN) : power off 11Users: HAL 12 13What: /sys/class/backlight/<backlight>/brightness 14Date: April 2005 15KernelVersion: 2.6.12 16Contact: Richard Purdie <rpurdie@rpsys.net> 17Description: 18 Control the brightness for this <backlight>. Values 19 are between 0 and max_brightness. This file will also 20 show the brightness level stored in the driver, which 21 may not be the actual brightness (see actual_brightness). 22Users: HAL 23 24What: /sys/class/backlight/<backlight>/actual_brightness 25Date: March 2006 26KernelVersion: 2.6.17 27Contact: Richard Purdie <rpurdie@rpsys.net> 28Description: 29 Show the actual brightness by querying the hardware. 30Users: HAL 31 32What: /sys/class/backlight/<backlight>/max_brightness 33Date: April 2005 34KernelVersion: 2.6.12 35Contact: Richard Purdie <rpurdie@rpsys.net> 36Description: 37 Maximum brightness for <backlight>. 38Users: HAL 39 40What: /sys/class/backlight/<backlight>/type 41Date: September 2010 42KernelVersion: 2.6.37 43Contact: Matthew Garrett <mjg@redhat.com> 44Description: 45 The type of interface controlled by <backlight>. 46 "firmware": The driver uses a standard firmware interface 47 "platform": The driver uses a platform-specific interface 48 "raw": The driver controls hardware registers directly 49 50 In the general case, when multiple backlight 51 interfaces are available for a single device, firmware 52 control should be preferred to platform control should 53 be preferred to raw control. Using a firmware 54 interface reduces the probability of confusion with 55 the hardware and the OS independently updating the 56 backlight state. Platform interfaces are mostly a 57 holdover from pre-standardisation of firmware 58 interfaces. 59