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authorKrzysztof Kozlowski <krzk@kernel.org>2019-01-09 15:44:45 +0100
committerJacek Anaszewski <jacek.anaszewski@gmail.com>2019-01-16 22:06:51 +0100
commit1dd7093742517b4aa362d22eaff8eef133d876ce (patch)
tree7fa9bf1b506c7774ebae228aea28c9471f3241f6 /Documentation/ABI/testing
parentLinux 5.0-rc1 (diff)
downloadlinux-1dd7093742517b4aa362d22eaff8eef133d876ce.tar.xz
linux-1dd7093742517b4aa362d22eaff8eef133d876ce.zip
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: Krzysztof Kozlowski <krzk@kernel.org> Acked-by: Pavel Machek <pavel@ucw.cz> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Diffstat (limited to 'Documentation/ABI/testing')
-rw-r--r--Documentation/ABI/testing/sysfs-class-led-trigger-pattern51
1 files changed, 3 insertions, 48 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
index 1e5d172e0646..bd92ef9d6faa 100644
--- a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
+++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
@@ -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