0001 What: /sys/class/backlight/<backlight>/bl_power
0002 Date: April 2005
0003 KernelVersion: 2.6.12
0004 Contact: Richard Purdie <rpurdie@rpsys.net>
0005 Description:
0006 Control BACKLIGHT power, values are FB_BLANK_* from fb.h
0007
0008 - FB_BLANK_UNBLANK (0) : power on.
0009 - FB_BLANK_POWERDOWN (4) : power off
0010 Users: HAL
0011
0012 What: /sys/class/backlight/<backlight>/brightness
0013 Date: April 2005
0014 KernelVersion: 2.6.12
0015 Contact: Richard Purdie <rpurdie@rpsys.net>
0016 Description:
0017 Control the brightness for this <backlight>. Values
0018 are between 0 and max_brightness. This file will also
0019 show the brightness level stored in the driver, which
0020 may not be the actual brightness (see actual_brightness).
0021 Users: HAL
0022
0023 What: /sys/class/backlight/<backlight>/actual_brightness
0024 Date: March 2006
0025 KernelVersion: 2.6.17
0026 Contact: Richard Purdie <rpurdie@rpsys.net>
0027 Description:
0028 Show the actual brightness by querying the hardware.
0029 Users: HAL
0030
0031 What: /sys/class/backlight/<backlight>/max_brightness
0032 Date: April 2005
0033 KernelVersion: 2.6.12
0034 Contact: Richard Purdie <rpurdie@rpsys.net>
0035 Description:
0036 Maximum brightness for <backlight>.
0037 Users: HAL
0038
0039 What: /sys/class/backlight/<backlight>/type
0040 Date: September 2010
0041 KernelVersion: 2.6.37
0042 Contact: Matthew Garrett <mjg@redhat.com>
0043 Description:
0044 The type of interface controlled by <backlight>.
0045 "firmware": The driver uses a standard firmware interface
0046 "platform": The driver uses a platform-specific interface
0047 "raw": The driver controls hardware registers directly
0048
0049 In the general case, when multiple backlight
0050 interfaces are available for a single device, firmware
0051 control should be preferred to platform control should
0052 be preferred to raw control. Using a firmware
0053 interface reduces the probability of confusion with
0054 the hardware and the OS independently updating the
0055 backlight state. Platform interfaces are mostly a
0056 holdover from pre-standardisation of firmware
0057 interfaces.
