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+* Pattern format for LED pattern trigger
+
+The pattern is given by a series of tuples, of brightness and duration (ms).
+The LED is expected to traverse the series and each brightness value for the
+specified duration. Duration of 0 means brightness should immediately change to
+new value, and writing malformed pattern deactivates any active one.
+
+1. For gradual dimming, the dimming interval now is set as 50 milliseconds. So
+the tuple with duration less than dimming interval (50ms) is treated as a step
+change of brightness, i.e. the subsequent brightness will be applied without
+adding intervening dimming intervals.
+
+The gradual dimming format of the software pattern values should be:
+"brightness_1 duration_1 brightness_2 duration_2 brightness_3 duration_3 ...".
+For example (using sysfs interface):
+
+echo 0 1000 255 2000 > pattern
+
+It will make the LED go gradually from zero-intensity to max (255) intensity in
+1000 milliseconds, then back to zero intensity in 2000 milliseconds:
+
+LED brightness
+ ^
+255-| / \ / \ /
+ | / \ / \ /
+ | / \ / \ /
+ | / \ / \ /
+ 0-| / \/ \/
+ +---0----1----2----3----4----5----6------------> time (s)
+
+2. To make the LED go instantly from one brightness value to another, we should
+use zero-time lengths (the brightness must be same as the previous tuple's). So
+the format should be: "brightness_1 duration_1 brightness_1 0 brightness_2
+duration_2 brightness_2 0 ...".
+For example (using sysfs interface):
+
+echo 0 1000 0 0 255 2000 255 0 > pattern
+
+It will make the LED stay off for one second, then stay at max brightness for
+two seconds:
+
+LED brightness
+ ^
+255-| +---------+ +---------+
+ | | | | |
+ | | | | |
+ | | | | |
+ 0-| -----+ +----+ +----
+ +---0----1----2----3----4----5----6------------> time (s)