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