| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | What: /sys/class/leds/<led>/brightness |
| 2 | Date: March 2006 |
| 3 | KernelVersion: 2.6.17 |
| 4 | Contact: Richard Purdie <rpurdie@rpsys.net> |
| 5 | Description: |
| 6 | Set the brightness of the LED. Most LEDs don't |
| 7 | have hardware brightness support, so will just be turned on for |
| 8 | non-zero brightness settings. The value is between 0 and |
| 9 | /sys/class/leds/<led>/max_brightness. |
| 10 | |
| 11 | Writing 0 to this file clears active trigger. |
| 12 | |
| 13 | Writing non-zero to this file while trigger is active changes the |
| 14 | top brightness trigger is going to use. |
| 15 | |
| 16 | What: /sys/class/leds/<led>/max_brightness |
| 17 | Date: March 2006 |
| 18 | KernelVersion: 2.6.17 |
| 19 | Contact: Richard Purdie <rpurdie@rpsys.net> |
| 20 | Description: |
| 21 | Maximum brightness level for this LED, default is 255 (LED_FULL). |
| 22 | |
| 23 | If the LED does not support different brightness levels, this |
| 24 | should be 1. |
| 25 | |
| 26 | What: /sys/class/leds/<led>/brightness_hw_changed |
| 27 | Date: January 2017 |
| 28 | KernelVersion: 4.11 |
| 29 | Description: |
| 30 | Last hardware set brightness level for this LED. Some LEDs |
| 31 | may be changed autonomously by hardware/firmware. Only LEDs |
| 32 | where this happens and the driver can detect this, will have |
| 33 | this file. |
| 34 | |
| 35 | This file supports poll() to detect when the hardware changes |
| 36 | the brightness. |
| 37 | |
| 38 | Reading this file will return the last brightness level set |
| 39 | by the hardware, this may be different from the current |
| 40 | brightness. Reading this file when no hw brightness change |
| 41 | event has happened will return an ENODATA error. |
| 42 | |
| 43 | What: /sys/class/leds/<led>/trigger |
| 44 | Date: March 2006 |
| 45 | KernelVersion: 2.6.17 |
| 46 | Contact: Richard Purdie <rpurdie@rpsys.net> |
| 47 | Description: |
| 48 | Set the trigger for this LED. A trigger is a kernel based source |
| 49 | of LED events. |
| 50 | You can change triggers in a similar manner to the way an IO |
| 51 | scheduler is chosen. Trigger specific parameters can appear in |
| 52 | /sys/class/leds/<led> once a given trigger is selected. For |
| 53 | their documentation see sysfs-class-led-trigger-*. |
| 54 | |
| 55 | What: /sys/class/leds/<led>/inverted |
| 56 | Date: January 2011 |
| 57 | KernelVersion: 2.6.38 |
| 58 | Contact: Richard Purdie <rpurdie@rpsys.net> |
| 59 | Description: |
| 60 | Invert the LED on/off state. This parameter is specific to |
| 61 | gpio and backlight triggers. In case of the backlight trigger, |
| 62 | it is useful when driving a LED which is intended to indicate |
| 63 | a device in a standby like state. |