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author | Krzysztof Kozlowski <krzk@kernel.org> | 2019-01-09 15:44:45 +0100 |
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committer | Jacek Anaszewski <jacek.anaszewski@gmail.com> | 2019-01-16 22:06:51 +0100 |
commit | 1dd7093742517b4aa362d22eaff8eef133d876ce (patch) | |
tree | 7fa9bf1b506c7774ebae228aea28c9471f3241f6 /Documentation/ABI | |
parent | bfeffd155283772bbe78c6a05dec7c0128ee500c (diff) | |
download | linux-1dd7093742517b4aa362d22eaff8eef133d876ce.tar.bz2 |
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')
-rw-r--r-- | Documentation/ABI/testing/sysfs-class-led-trigger-pattern | 51 |
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 |