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

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

+ 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

(cesky, pictures)
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at