| What: /sys/class/leds/<led>/brightness |
| Date: March 2006 |
| KernelVersion: 2.6.17 |
| Contact: Richard Purdie <rpurdie@rpsys.net> |
| Description: |
| Set the brightness of the LED. Most LEDs don't |
| have hardware brightness support, so will just be turned on for |
| non-zero brightness settings. The value is between 0 and |
| /sys/class/leds/<led>/max_brightness. |
| |
| Writing 0 to this file clears active trigger. |
| |
| Writing non-zero to this file while trigger is active changes the |
| top brightness trigger is going to use. |
| |
| What: /sys/class/leds/<led>/max_brightness |
| Date: March 2006 |
| KernelVersion: 2.6.17 |
| Contact: Richard Purdie <rpurdie@rpsys.net> |
| Description: |
| Maximum brightness level for this LED, default is 255 (LED_FULL). |
| |
| If the LED does not support different brightness levels, this |
| should be 1. |
| |
| What: /sys/class/leds/<led>/brightness_hw_changed |
| Date: January 2017 |
| KernelVersion: 4.11 |
| Description: |
| Last hardware set brightness level for this LED. Some LEDs |
| may be changed autonomously by hardware/firmware. Only LEDs |
| where this happens and the driver can detect this, will have |
| this file. |
| |
| This file supports poll() to detect when the hardware changes |
| the brightness. |
| |
| Reading this file will return the last brightness level set |
| by the hardware, this may be different from the current |
| brightness. Reading this file when no hw brightness change |
| event has happened will return an ENODATA error. |
| |
| What: /sys/class/leds/<led>/trigger |
| Date: March 2006 |
| KernelVersion: 2.6.17 |
| Contact: Richard Purdie <rpurdie@rpsys.net> |
| Description: |
| Set the trigger for this LED. A trigger is a kernel based source |
| of LED events. |
| You can change triggers in a similar manner to the way an IO |
| scheduler is chosen. Trigger specific parameters can appear in |
| /sys/class/leds/<led> once a given trigger is selected. For |
| their documentation see sysfs-class-led-trigger-*. |
| |
| What: /sys/class/leds/<led>/inverted |
| Date: January 2011 |
| KernelVersion: 2.6.38 |
| Contact: Richard Purdie <rpurdie@rpsys.net> |
| Description: |
| Invert the LED on/off state. This parameter is specific to |
| gpio and backlight triggers. In case of the backlight trigger, |
| it is useful when driving a LED which is intended to indicate |
| a device in a standby like state. |