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