Files
kernel_xiaomi_sm8450-device…/bindings/leds/leds-trigger-pattern.txt
Venkata Narendra Kumar Gutta b0e5152a74 dt-bindings: Add devicetree bindings to devicetree project
Add devicetree bindings snapshot to the devicetree project.
This snapshot is taken as of the
'commit 5fba1b18cfc72e264e5f3ce49020ed322aa6ac9f ("Merge 5.6-rc3
into android-mainline")' of the kernel project.

Change-Id: Ia087ab2b7d4a2616ea446a69683a8b5b821d0448
2020-05-07 20:43:53 -07:00

50 lines
2.0 KiB
Plaintext

* 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)