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1What: /sys/class/backlight/<backlight>/bl_power2Date: April 20053KernelVersion: 2.6.124Contact: Richard Purdie <rpurdie@rpsys.net>5Description:6 Control BACKLIGHT power, values are compatible with7 FB_BLANK_* from fb.h8 9 - 0 (FB_BLANK_UNBLANK) : power on.10 - 4 (FB_BLANK_POWERDOWN) : power off11Users: HAL12 13What: /sys/class/backlight/<backlight>/brightness14Date: April 200515KernelVersion: 2.6.1216Contact: Richard Purdie <rpurdie@rpsys.net>17Description:18 Control the brightness for this <backlight>. Values19 are between 0 and max_brightness. This file will also20 show the brightness level stored in the driver, which21 may not be the actual brightness (see actual_brightness).22Users: HAL23 24What: /sys/class/backlight/<backlight>/actual_brightness25Date: March 200626KernelVersion: 2.6.1727Contact: Richard Purdie <rpurdie@rpsys.net>28Description:29 Show the actual brightness by querying the hardware.30Users: HAL31 32What: /sys/class/backlight/<backlight>/max_brightness33Date: April 200534KernelVersion: 2.6.1235Contact: Richard Purdie <rpurdie@rpsys.net>36Description:37 Maximum brightness for <backlight>.38Users: HAL39 40What: /sys/class/backlight/<backlight>/type41Date: September 201042KernelVersion: 2.6.3743Contact: Matthew Garrett <mjg@redhat.com>44Description:45 The type of interface controlled by <backlight>.46 "firmware": The driver uses a standard firmware interface47 "platform": The driver uses a platform-specific interface48 "raw": The driver controls hardware registers directly49 50 In the general case, when multiple backlight51 interfaces are available for a single device, firmware52 control should be preferred to platform control should53 be preferred to raw control. Using a firmware54 interface reduces the probability of confusion with55 the hardware and the OS independently updating the56 backlight state. Platform interfaces are mostly a57 holdover from pre-standardisation of firmware58 interfaces.59