1What: /sys/class/leds/<led>/brightness 2Date: March 2006 3KernelVersion: 2.6.17 4Contact: Richard Purdie <rpurdie@rpsys.net> 5Description: 6 Set the brightness of the LED. 7 8 Most LEDs don't have hardware brightness support, so will 9 just be turned on for non-zero brightness settings. 10 11 .. Note:: 12 13 For multicolor LEDs, writing to this file will update all 14 LEDs within the group to a calculated percentage of what 15 each color LED intensity is set to. 16 17 The percentage is calculated for each grouped LED via 18 the equation below:: 19 20 led_brightness = brightness * multi_intensity/max_brightness 21 22 For additional details please refer to 23 Documentation/leds/leds-class-multicolor.rst. 24 25 The value is between 0 and 26 /sys/class/leds/<led>/max_brightness. 27 28 Writing 0 to this file clears active trigger. 29 30 Writing non-zero to this file while trigger is active changes the 31 top brightness trigger is going to use. 32 33 34 35What: /sys/class/leds/<led>/max_brightness 36Date: March 2006 37KernelVersion: 2.6.17 38Contact: Richard Purdie <rpurdie@rpsys.net> 39Description: 40 Maximum brightness level for this LED, default is 255 (LED_FULL). 41 42 If the LED does not support different brightness levels, this 43 should be 1. 44 45What: /sys/class/leds/<led>/brightness_hw_changed 46Date: January 2017 47KernelVersion: 4.11 48Description: 49 Last hardware set brightness level for this LED. Some LEDs 50 may be changed autonomously by hardware/firmware. Only LEDs 51 where this happens and the driver can detect this, will have 52 this file. 53 54 This file supports poll() to detect when the hardware changes 55 the brightness. 56 57 Reading this file will return the last brightness level set 58 by the hardware, this may be different from the current 59 brightness. Reading this file when no hw brightness change 60 event has happened will return an ENODATA error. 61 62What: /sys/class/leds/<led>/trigger 63Date: March 2006 64KernelVersion: 2.6.17 65Contact: Richard Purdie <rpurdie@rpsys.net> 66Description: 67 Set the trigger for this LED. A trigger is a kernel based source 68 of LED events. 69 70 You can change triggers in a similar manner to the way an IO 71 scheduler is chosen. Trigger specific parameters can appear in 72 /sys/class/leds/<led> once a given trigger is selected. For 73 their documentation see `sysfs-class-led-trigger-*`. 74 75What: /sys/class/leds/<led>/inverted 76Date: January 2011 77KernelVersion: 2.6.38 78Contact: Richard Purdie <rpurdie@rpsys.net> 79Description: 80 Invert the LED on/off state. This parameter is specific to 81 gpio and backlight triggers. In case of the backlight trigger, 82 it is useful when driving a LED which is intended to indicate 83 a device in a standby like state. 84