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# SPDX-License-Identifier: GPL-2.0-only
%YAML 1.2
---
$id: http://devicetree.org/schemas/leds/backlight/pwm-backlight.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: pwm-backlight
maintainers:
- Lee Jones <lee@kernel.org>
- Daniel Thompson <daniel.thompson@linaro.org>
- Jingoo Han <jingoohan1@gmail.com>
properties:
compatible:
const: pwm-backlight
pwms:
maxItems: 1
pwm-names: true
power-supply:
description: regulator for supply voltage
enable-gpios:
description:
Contains a single GPIO specifier for the GPIO which enables and disables
the backlight.
maxItems: 1
post-pwm-on-delay-ms:
description:
Delay in ms between setting an initial (non-zero) PWM and enabling the
backlight using GPIO.
pwm-off-delay-ms:
description:
Delay in ms between disabling the backlight using GPIO and setting PWM
value to 0.
brightness-levels:
description:
Array of distinct brightness levels. Typically these are in the range
from 0 to 255, but any range starting at 0 will do. The actual brightness
level (PWM duty cycle) will be interpolated from these values. 0 means a
0% duty cycle (darkest/off), while the last value in the array represents
a 100% duty cycle (brightest).
$ref: /schemas/types.yaml#/definitions/uint32-array
default-brightness-level:
description:
The default brightness level (index into the array defined by the
"brightness-levels" property).
$ref: /schemas/types.yaml#/definitions/uint32
num-interpolated-steps:
description:
Number of interpolated steps between each value of brightness-levels
table. This way a high resolution pwm duty cycle can be used without
having to list out every possible value in the brightness-level array.
$ref: /schemas/types.yaml#/definitions/uint32
dependencies:
default-brightness-level: [brightness-levels]
num-interpolated-steps: [brightness-levels]
required:
- compatible
- pwms
additionalProperties: false
examples:
- |
backlight {
compatible = "pwm-backlight";
pwms = <&pwm 0 5000000>;
brightness-levels = <0 4 8 16 32 64 128 255>;
default-brightness-level = <6>;
power-supply = <&vdd_bl_reg>;
enable-gpios = <&gpio 58 0>;
post-pwm-on-delay-ms = <10>;
pwm-off-delay-ms = <10>;
};
- |
// Example using num-interpolation-steps:
backlight {
compatible = "pwm-backlight";
pwms = <&pwm 0 5000000>;
brightness-levels = <0 2048 4096 8192 16384 65535>;
num-interpolated-steps = <2048>;
default-brightness-level = <4096>;
power-supply = <&vdd_bl_reg>;
enable-gpios = <&gpio 58 0>;
};
...
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