From 9f9455ae710786bd11625d501567f4f783fedea5 Mon Sep 17 00:00:00 2001 From: Janusz Krzysztofik Date: Wed, 12 Jan 2011 16:59:20 -0800 Subject: leds: add output inversion option to backlight trigger 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 Cc: Paul Mundt Acked-by: Richard Purdie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/ABI/testing/sysfs-class-led | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation/ABI') diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led index 9e4541d71cb6..edff6630c805 100644 --- a/Documentation/ABI/testing/sysfs-class-led +++ b/Documentation/ABI/testing/sysfs-class-led @@ -26,3 +26,12 @@ Description: scheduler is chosen. Trigger specific parameters can appear in /sys/class/leds/ once a given trigger is selected. +What: /sys/class/leds//inverted +Date: January 2011 +KernelVersion: 2.6.38 +Contact: Richard Purdie +Description: + Invert the LED on/off state. This parameter is specific to + gpio and backlight triggers. In case of the backlight trigger, + it is usefull when driving a LED which is intended to indicate + a device in a standby like state. -- cgit v1.2.1