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.
|
|
.. Note::
|
|
For multicolor LEDs, writing to this file will update all
|
LEDs within the group to a calculated percentage of what
|
each color LED intensity is set to.
|
|
The percentage is calculated for each grouped LED via
|
the equation below::
|
|
led_brightness = brightness * multi_intensity/max_brightness
|
|
For additional details please refer to
|
Documentation/leds/leds-class-multicolor.rst.
|
|
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.
|
