# \[PATCH v6 2/5\] dt-bindings: pwm-backlight: add PWM delay proprieties.

- From: Enric Balletbo i Serra \<hidden\>
- Date: 2018-03-26 09:52:27 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2018/03/5243292
- Thread: https://ratatoskr.run/linux-pwm/2018/03/5243290/t.md

```text
Hardware needs a delay between setting an initial (non-zero) PWM and
enabling the backlight using GPIO. The post-pwm-on-delay-ms specifies
this delay in milli seconds. Hardware also needs a delay between disabing
the backlight using GPIO and setting PWM value to 0. The pwm-off-delay-ms
is this delay in milli seconds.

Signed-off-by: Enric Balletbo i Serra <redacted>
Acked-by: Pavel Machek <redacted>
Acked-by: Thierry Reding <redacted>
---
Based on the original Huang Lin [ref] work.
Changes since v5:
 - Add Acked-by: Thierry Reding [ref]
 - CC DT mainling list (for some reason dropped at some point, my
   fault)
Changes since v4:
 - Rebase on top of mainline.
Changes since v3:
 - Replace us for ms.
 - Add Acked-by: Pavel Machek [ref]
Changes since v2:
 - Use separate properties (Rob Herring)
Changes since v1:
 - As suggested by Daniel Thompson
   - Do not assume power-on delay and power-off delay will be the same
---
 Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
index 764db86d441a..310810906613 100644
--- a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
@@ -17,6 +17,10 @@ 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])
+  - post-pwm-on-delay-ms: Delay in ms between setting an initial (non-zero) PWM
+                          and enabling the backlight using GPIO.
+  - pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO
+                      and setting PWM value to 0.
 
 [0]: Documentation/devicetree/bindings/pwm/pwm.txt
 [1]: Documentation/devicetree/bindings/gpio/gpio.txt
@@ -32,4 +36,6 @@ Example:
 
 		power-supply = <&vdd_bl_reg>;
 		enable-gpios = <&gpio 58 0>;
+		post-pwm-on-delay-ms = <10>;
+		pwm-off-delay-ms = <10>;
 	};
-- 
2.16.2

```