1*4882a593SmuzhiyunWhat: /sys/class/leds/<led>/brightness 2*4882a593SmuzhiyunDate: March 2006 3*4882a593SmuzhiyunKernelVersion: 2.6.17 4*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 5*4882a593SmuzhiyunDescription: 6*4882a593Smuzhiyun Set the brightness of the LED. 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun Most LEDs don't have hardware brightness support, so will 9*4882a593Smuzhiyun just be turned on for non-zero brightness settings. 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun .. Note:: 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun For multicolor LEDs, writing to this file will update all 14*4882a593Smuzhiyun LEDs within the group to a calculated percentage of what 15*4882a593Smuzhiyun each color LED intensity is set to. 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun The percentage is calculated for each grouped LED via 18*4882a593Smuzhiyun the equation below:: 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun led_brightness = brightness * multi_intensity/max_brightness 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun For additional details please refer to 23*4882a593Smuzhiyun Documentation/leds/leds-class-multicolor.rst. 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun The value is between 0 and 26*4882a593Smuzhiyun /sys/class/leds/<led>/max_brightness. 27*4882a593Smuzhiyun 28*4882a593Smuzhiyun Writing 0 to this file clears active trigger. 29*4882a593Smuzhiyun 30*4882a593Smuzhiyun Writing non-zero to this file while trigger is active changes the 31*4882a593Smuzhiyun top brightness trigger is going to use. 32*4882a593Smuzhiyun 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun 35*4882a593SmuzhiyunWhat: /sys/class/leds/<led>/max_brightness 36*4882a593SmuzhiyunDate: March 2006 37*4882a593SmuzhiyunKernelVersion: 2.6.17 38*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 39*4882a593SmuzhiyunDescription: 40*4882a593Smuzhiyun Maximum brightness level for this LED, default is 255 (LED_FULL). 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun If the LED does not support different brightness levels, this 43*4882a593Smuzhiyun should be 1. 44*4882a593Smuzhiyun 45*4882a593SmuzhiyunWhat: /sys/class/leds/<led>/brightness_hw_changed 46*4882a593SmuzhiyunDate: January 2017 47*4882a593SmuzhiyunKernelVersion: 4.11 48*4882a593SmuzhiyunDescription: 49*4882a593Smuzhiyun Last hardware set brightness level for this LED. Some LEDs 50*4882a593Smuzhiyun may be changed autonomously by hardware/firmware. Only LEDs 51*4882a593Smuzhiyun where this happens and the driver can detect this, will have 52*4882a593Smuzhiyun this file. 53*4882a593Smuzhiyun 54*4882a593Smuzhiyun This file supports poll() to detect when the hardware changes 55*4882a593Smuzhiyun the brightness. 56*4882a593Smuzhiyun 57*4882a593Smuzhiyun Reading this file will return the last brightness level set 58*4882a593Smuzhiyun by the hardware, this may be different from the current 59*4882a593Smuzhiyun brightness. Reading this file when no hw brightness change 60*4882a593Smuzhiyun event has happened will return an ENODATA error. 61*4882a593Smuzhiyun 62*4882a593SmuzhiyunWhat: /sys/class/leds/<led>/trigger 63*4882a593SmuzhiyunDate: March 2006 64*4882a593SmuzhiyunKernelVersion: 2.6.17 65*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 66*4882a593SmuzhiyunDescription: 67*4882a593Smuzhiyun Set the trigger for this LED. A trigger is a kernel based source 68*4882a593Smuzhiyun of LED events. 69*4882a593Smuzhiyun 70*4882a593Smuzhiyun You can change triggers in a similar manner to the way an IO 71*4882a593Smuzhiyun scheduler is chosen. Trigger specific parameters can appear in 72*4882a593Smuzhiyun /sys/class/leds/<led> once a given trigger is selected. For 73*4882a593Smuzhiyun their documentation see `sysfs-class-led-trigger-*`. 74*4882a593Smuzhiyun 75*4882a593SmuzhiyunWhat: /sys/class/leds/<led>/inverted 76*4882a593SmuzhiyunDate: January 2011 77*4882a593SmuzhiyunKernelVersion: 2.6.38 78*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 79*4882a593SmuzhiyunDescription: 80*4882a593Smuzhiyun Invert the LED on/off state. This parameter is specific to 81*4882a593Smuzhiyun gpio and backlight triggers. In case of the backlight trigger, 82*4882a593Smuzhiyun it is useful when driving a LED which is intended to indicate 83*4882a593Smuzhiyun a device in a standby like state. 84