1 What: /sys/class/backlight/<backlight>/bl_power 2 Date: April 2005 3 KernelVersion: 2.6.12 4 Contact: Richard Purdie <rpurdie@rpsys.net> 5 Description: 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 11 Users: HAL 12 13 What: /sys/class/backlight/<backlight>/brightness 14 Date: April 2005 15 KernelVersion: 2.6.12 16 Contact: Richard Purdie <rpurdie@rpsys.net> 17 Description: 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). 22 Users: HAL 23 24 What: /sys/class/backlight/<backlight>/actual_brightness 25 Date: March 2006 26 KernelVersion: 2.6.17 27 Contact: Richard Purdie <rpurdie@rpsys.net> 28 Description: 29 Show the actual brightness by querying the hardware. 30 Users: HAL 31 32 What: /sys/class/backlight/<backlight>/max_brightness 33 Date: April 2005 34 KernelVersion: 2.6.12 35 Contact: Richard Purdie <rpurdie@rpsys.net> 36 Description: 37 Maximum brightness for <backlight>. 38 Users: HAL 39 40 What: /sys/class/backlight/<backlight>/type 41 Date: September 2010 42 KernelVersion: 2.6.37 43 Contact: Matthew Garrett <mjg@redhat.com> 44 Description: 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.
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