[PATCH 3/3] leds: update documentation about new delay units

From: Stas Sergeev
Date: Mon Apr 27 2015 - 13:14:33 EST

This adds the description of /sys/class/leds/<device>/delay_unit.
It allows you to specify the delay unit for the led trigger timer.

CC: Jonathan Corbet <corbet@xxxxxxx>
CC: linux-doc@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx

Signed-off-by: Stas Sergeev <stsp@xxxxxxxxxxxxxxxxxxxxx>
Documentation/leds/leds-class.txt | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index 79699c2..0e5ecf5 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -23,6 +23,10 @@ parameters and work on a per LED basis. The timer trigger is an example.
The timer trigger will periodically change the LED brightness between
LED_OFF and the current brightness setting. The "on" and "off" time can
be specified via /sys/class/leds/<device>/delay_{on,off} in milliseconds.
+If you want to specify the delay in microseconds or nanoseconds, you can
+write 'usec' or 'nsec' to /sys/class/leds/<device>/delay_unit. That
+functionality is available only if you have high-resolution timers
+configured (check CONFIG_HIGH_RES_TIMERS in your kernel config).
You can change the brightness value of a LED independently of the timer
trigger. However, if you set the brightness value to LED_OFF it will
also disable the timer trigger.
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