9f9455ae71
Extend the LED backlight tirgger driver with an option that allows for inverting the trigger output polarity. With the invertion option provided, I (ab)use the backlight trigger for driving a LED that indicates LCD display blank condtition on my Amstrad Delta videophone. Since the machine has no dedicated power LED, it was not possible to distinguish if the display was blanked, or the machine was turned off, without touching it. The invert sysfs control is patterned after a similiar function of the GPIO trigger driver. [akpm@linux-foundation.org: make output match input, tighten input checking] [akpm@linux-foundation.org: make output match input, tighten input checking] Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> Cc: Paul Mundt <lethal@linux-sh.org> Acked-by: Richard Purdie <richard.purdie@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
37 lines
1.3 KiB
Text
37 lines
1.3 KiB
Text
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. Most LEDs don't
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have hardware brightness support so will just be turned on for
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non-zero brightness settings. The value is between 0 and
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/sys/class/leds/<led>/max_brightness.
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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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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.
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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 usefull when driving a LED which is intended to indicate
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a device in a standby like state.
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