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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
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treeb2d64bc10158fdd5497876388cd68142ca374ed3 /Documentation/ABI/testing/sysfs-class-led
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
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Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+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.