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Linux kernel mirror (for testing)
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linux
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. Due
30 to implementation differences in hardware this may not
31 match the value in 'brightness'. For example some hardware
32 may treat blanking differently or have custom power saving
33 features. Userspace should generally use the values in
34 'brightness' to make decisions.
35Users: HAL
36
37What: /sys/class/backlight/<backlight>/max_brightness
38Date: April 2005
39KernelVersion: 2.6.12
40Contact: Richard Purdie <rpurdie@rpsys.net>
41Description:
42 Maximum brightness for <backlight>.
43Users: HAL
44
45What: /sys/class/backlight/<backlight>/type
46Date: September 2010
47KernelVersion: 2.6.37
48Contact: Matthew Garrett <mjg@redhat.com>
49Description:
50 The type of interface controlled by <backlight>.
51 "firmware": The driver uses a standard firmware interface
52 "platform": The driver uses a platform-specific interface
53 "raw": The driver controls hardware registers directly
54
55 In the general case, when multiple backlight
56 interfaces are available for a single device, firmware
57 control should be preferred to platform control should
58 be preferred to raw control. Using a firmware
59 interface reduces the probability of confusion with
60 the hardware and the OS independently updating the
61 backlight state. Platform interfaces are mostly a
62 holdover from pre-standardisation of firmware
63 interfaces.