Documentation: leds: clarify what 50% brightness means

From: Pavel Machek
Date: Wed Mar 11 2015 - 05:34:36 EST


I played with RGB LED a bit, and we have quite a gap in
documentation: what 50% brightness means is non-trivial and very
important in case we want to do smooth blinking and color
transitions.

Signed-off-by: Pavel Machek <pavel@xxxxxx>

diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 3646ec8..649d7a6 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -8,6 +8,11 @@ Description:
non-zero brightness settings. The value is between 0 and
/sys/class/leds/<led>/max_brightness.

+ If LED supports continuous brightness settings, 50% brightness
+ should correspond to 50% brightness perceived by human, in a similar
+ manner pixel brightness on monitor does (not 50% PWM).
+
+
What: /sys/class/leds/<led>/max_brightness
Date: March 2006
KernelVersion: 2.6.17

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