1 What: /sys/class/backlight/<backligh 1 What: /sys/class/backlight/<backlight>/bl_power
2 Date: April 2005 2 Date: April 2005
3 KernelVersion: 2.6.12 3 KernelVersion: 2.6.12
4 Contact: Richard Purdie <rpurdie@rpsys.n 4 Contact: Richard Purdie <rpurdie@rpsys.net>
5 Description: 5 Description:
6 Control BACKLIGHT power, value 6 Control BACKLIGHT power, values are compatible with
7 FB_BLANK_* from fb.h 7 FB_BLANK_* from fb.h
8 8
9 - 0 (FB_BLANK_UNBLANK) : po 9 - 0 (FB_BLANK_UNBLANK) : power on.
10 - 4 (FB_BLANK_POWERDOWN) : po 10 - 4 (FB_BLANK_POWERDOWN) : power off
11 Users: HAL 11 Users: HAL
12 12
13 What: /sys/class/backlight/<backligh 13 What: /sys/class/backlight/<backlight>/brightness
14 Date: April 2005 14 Date: April 2005
15 KernelVersion: 2.6.12 15 KernelVersion: 2.6.12
16 Contact: Richard Purdie <rpurdie@rpsys.n 16 Contact: Richard Purdie <rpurdie@rpsys.net>
17 Description: 17 Description:
18 Control the brightness for thi 18 Control the brightness for this <backlight>. Values
19 are between 0 and max_brightne 19 are between 0 and max_brightness. This file will also
20 show the brightness level stor 20 show the brightness level stored in the driver, which
21 may not be the actual brightne 21 may not be the actual brightness (see actual_brightness).
22 Users: HAL 22 Users: HAL
23 23
24 What: /sys/class/backlight/<backligh 24 What: /sys/class/backlight/<backlight>/actual_brightness
25 Date: March 2006 25 Date: March 2006
26 KernelVersion: 2.6.17 26 KernelVersion: 2.6.17
27 Contact: Richard Purdie <rpurdie@rpsys.n 27 Contact: Richard Purdie <rpurdie@rpsys.net>
28 Description: 28 Description:
29 Show the actual brightness by 29 Show the actual brightness by querying the hardware.
30 Users: HAL 30 Users: HAL
31 31
32 What: /sys/class/backlight/<backligh 32 What: /sys/class/backlight/<backlight>/max_brightness
33 Date: April 2005 33 Date: April 2005
34 KernelVersion: 2.6.12 34 KernelVersion: 2.6.12
35 Contact: Richard Purdie <rpurdie@rpsys.n 35 Contact: Richard Purdie <rpurdie@rpsys.net>
36 Description: 36 Description:
37 Maximum brightness for <backli 37 Maximum brightness for <backlight>.
38 Users: HAL 38 Users: HAL
39 39
40 What: /sys/class/backlight/<backligh 40 What: /sys/class/backlight/<backlight>/type
41 Date: September 2010 41 Date: September 2010
42 KernelVersion: 2.6.37 42 KernelVersion: 2.6.37
43 Contact: Matthew Garrett <mjg@redhat.com 43 Contact: Matthew Garrett <mjg@redhat.com>
44 Description: 44 Description:
45 The type of interface controll 45 The type of interface controlled by <backlight>.
46 "firmware": The driver uses a 46 "firmware": The driver uses a standard firmware interface
47 "platform": The driver uses a 47 "platform": The driver uses a platform-specific interface
48 "raw": The driver controls har 48 "raw": The driver controls hardware registers directly
49 49
50 In the general case, when mult 50 In the general case, when multiple backlight
51 interfaces are available for a 51 interfaces are available for a single device, firmware
52 control should be preferred to 52 control should be preferred to platform control should
53 be preferred to raw control. U 53 be preferred to raw control. Using a firmware
54 interface reduces the probabil 54 interface reduces the probability of confusion with
55 the hardware and the OS indepe 55 the hardware and the OS independently updating the
56 backlight state. Platform inte 56 backlight state. Platform interfaces are mostly a
57 holdover from pre-standardisat 57 holdover from pre-standardisation of firmware
58 interfaces. 58 interfaces.
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