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authorJanusz Krzysztofik <jkrzyszt@tis.icnet.pl>2011-01-12 16:59:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 08:03:06 -0800
commit9f9455ae710786bd11625d501567f4f783fedea5 (patch)
tree6ce8c8b1d8a4fb58d85484555ea25b2a6d298796 /Documentation
parent61a83932b8b3f1624d753e06aab2fdf0a119e100 (diff)
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 <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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-class-led9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 9e4541d71cb..edff6630c80 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/<led> once a given trigger is selected.
+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 usefull when driving a LED which is intended to indicate
+ a device in a standby like state.