Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1dd70937 authored by Krzysztof Kozlowski's avatar Krzysztof Kozlowski Committed by Jacek Anaszewski
Browse files

dt-bindings: leds: Add pattern initialization from Device Tree 



Document new led-pattern property for initialization of LED triggers.
The property format is trigger-specific (except being array of
integers).  For pattern trigger, the explanation of pattern format was
moved to a common file shared with sysfs ABI.

Signed-off-by: default avatarKrzysztof Kozlowski <krzk@kernel.org>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarJacek Anaszewski <jacek.anaszewski@gmail.com>
parent bfeffd15

Documentation/ABI/testing/sysfs-class-led-trigger-pattern

+3 −48
Original line number Diff line number Diff line
@@ -7,55 +7,10 @@ Description: 
		timer. It can do gradual dimming and step change of brightness.



		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.

		duration (ms).



		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:



		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:



		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)

		The exact format is described in:

		Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt



What:		/sys/class/leds/<led>/hw_pattern

Date:		September 2018

Documentation/devicetree/bindings/leds/common.txt

+12 −0
Original line number Diff line number Diff line
@@ -37,6 +37,18 @@ Optional properties for child nodes: 
     "ide-disk" - LED indicates IDE disk activity (deprecated),

                  in new implementations use "disk-activity"

     "timer" - LED flashes at a fixed, configurable rate

     "pattern" - LED alters the brightness for the specified duration with one

                 software timer (requires "led-pattern" property)



- led-pattern : Array of integers with default pattern for certain triggers.

                Each trigger may parse this property differently:

                - one-shot : two numbers specifying delay on and delay off (in ms),

                - timer : two numbers specifying delay on and delay off (in ms),

                - pattern : the pattern is given by a series of tuples, of

                  brightness and duration (in ms).  The exact format is

                  described in:

                  Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt





- led-max-microamp : Maximum LED supply current in microamperes. This property

                     can be made mandatory for the board configurations

Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt

0 → 100644
+49 −0
Original line number Diff line number Diff line 
* 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)