1 What: /sys/class/leds/<led>/brightne 1 What: /sys/class/leds/<led>/brightness
2 Date: March 2006 2 Date: March 2006
3 KernelVersion: 2.6.17 3 KernelVersion: 2.6.17
4 Contact: Richard Purdie <rpurdie@rpsys.n 4 Contact: Richard Purdie <rpurdie@rpsys.net>
5 Description: 5 Description:
6 Set the brightness of the LED. !! 6 Set the brightness of the LED. Most LEDs don't
7 !! 7 have hardware brightness support, so will just be turned on for
8 Most LEDs don't have hardware !! 8 non-zero brightness settings. The value is between 0 and
9 just be turned on for non-zero <<
10 <<
11 .. Note:: <<
12 <<
13 For multicolor LEDs, writing <<
14 LEDs within the group to a c <<
15 each color LED intensity is <<
16 <<
17 The percentage is calculated <<
18 the equation below:: <<
19 <<
20 led_brightness = brightnes <<
21 <<
22 For additional details pleas <<
23 Documentation/leds/leds-clas <<
24 <<
25 The value is between 0 and <<
26 /sys/class/leds/<led>/max_brig 9 /sys/class/leds/<led>/max_brightness.
27 10
28 Writing 0 to this file clears 11 Writing 0 to this file clears active trigger.
29 12
30 Writing non-zero to this file 13 Writing non-zero to this file while trigger is active changes the
31 top brightness trigger is goin 14 top brightness trigger is going to use.
32 15
33 <<
34 <<
35 What: /sys/class/leds/<led>/max_brig 16 What: /sys/class/leds/<led>/max_brightness
36 Date: March 2006 17 Date: March 2006
37 KernelVersion: 2.6.17 18 KernelVersion: 2.6.17
38 Contact: Richard Purdie <rpurdie@rpsys.n 19 Contact: Richard Purdie <rpurdie@rpsys.net>
39 Description: 20 Description:
40 Maximum brightness level for t 21 Maximum brightness level for this LED, default is 255 (LED_FULL).
41 22
42 If the LED does not support di 23 If the LED does not support different brightness levels, this
43 should be 1. 24 should be 1.
44 25
45 What: /sys/class/leds/<led>/brightne 26 What: /sys/class/leds/<led>/brightness_hw_changed
46 Date: January 2017 27 Date: January 2017
47 KernelVersion: 4.11 28 KernelVersion: 4.11
48 Description: 29 Description:
49 Last hardware set brightness l 30 Last hardware set brightness level for this LED. Some LEDs
50 may be changed autonomously by 31 may be changed autonomously by hardware/firmware. Only LEDs
51 where this happens and the dri 32 where this happens and the driver can detect this, will have
52 this file. 33 this file.
53 34
54 This file supports poll() to d 35 This file supports poll() to detect when the hardware changes
55 the brightness. 36 the brightness.
56 37
57 Reading this file will return 38 Reading this file will return the last brightness level set
58 by the hardware, this may be d 39 by the hardware, this may be different from the current
59 brightness. Reading this file 40 brightness. Reading this file when no hw brightness change
60 event has happened will return 41 event has happened will return an ENODATA error.
61 42
62 What: /sys/class/leds/<led>/trigger 43 What: /sys/class/leds/<led>/trigger
63 Date: March 2006 44 Date: March 2006
64 KernelVersion: 2.6.17 45 KernelVersion: 2.6.17
65 Contact: Richard Purdie <rpurdie@rpsys.n 46 Contact: Richard Purdie <rpurdie@rpsys.net>
66 Description: 47 Description:
67 Set the trigger for this LED. 48 Set the trigger for this LED. A trigger is a kernel based source
68 of LED events. 49 of LED events.
69 <<
70 You can change triggers in a s 50 You can change triggers in a similar manner to the way an IO
71 scheduler is chosen. Trigger s 51 scheduler is chosen. Trigger specific parameters can appear in
72 /sys/class/leds/<led> once a g 52 /sys/class/leds/<led> once a given trigger is selected. For
73 their documentation see `sysfs !! 53 their documentation see sysfs-class-led-trigger-*.
74 54
75 What: /sys/class/leds/<led>/inverted 55 What: /sys/class/leds/<led>/inverted
76 Date: January 2011 56 Date: January 2011
77 KernelVersion: 2.6.38 57 KernelVersion: 2.6.38
78 Contact: Richard Purdie <rpurdie@rpsys.n 58 Contact: Richard Purdie <rpurdie@rpsys.net>
79 Description: 59 Description:
80 Invert the LED on/off state. T 60 Invert the LED on/off state. This parameter is specific to
81 gpio and backlight triggers. I 61 gpio and backlight triggers. In case of the backlight trigger,
82 it is useful when driving a LE 62 it is useful when driving a LED which is intended to indicate
83 a device in a standby like sta 63 a device in a standby like state.
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