Re: [PATCH 1/2] dt-bindings: pwm-backlight: Add pwm-delay-us property

From: Daniel Thompson
Date: Wed Jun 28 2017 - 09:17:26 EST


On 28/06/17 12:16, Enric Balletbo i Serra wrote:
From: huang lin <hl@xxxxxxxxxxxxxx>

Add a pwm-delay-us property to specify the delay between setting an
initial (non-zero) PWM value and enabling the backlight, and also the
delay between disabling the backlight and setting PWM value to 0.

Signed-off-by: huang lin <hl@xxxxxxxxxxxxxx>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
---
Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
index 764db86..f75b08f 100644
--- a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
@@ -17,6 +17,9 @@ Optional properties:
"pwms" property (see PWM binding[0])
- enable-gpios: contains a single GPIO specifier for the GPIO which enables
and disables the backlight (see GPIO binding[1])
+ - pwm-delay-us: delay between setting an initial (non-zero) PWM value and
+ enabling the backlight, and also the delay between disabling
+ the backlight and setting PWM value to 0.

If is safe to assume power-on delay and power-off delay will be the same?

I've only took a quick look but several backlight controllers support asymetric power-on/off sequences...


Daniel.


[0]: Documentation/devicetree/bindings/pwm/pwm.txt
[1]: Documentation/devicetree/bindings/gpio/gpio.txt
@@ -32,4 +35,5 @@ Example:
power-supply = <&vdd_bl_reg>;
enable-gpios = <&gpio 58 0>;
+ pwm-delay-us = <10000>;
};