On Mon, Oct 30, 2017 at 5:33 AM, Lee Jones [off-list ref] wrote:

On Fri, 27 Oct 2017, Rob Herring wrote:

quoted

On Thu, Oct 26, 2017 at 02:49:46PM +0200, Lothar Waßmann wrote:

quoted

When switching the backlight on, the LCD may need some time to adjust
to the configured PWM duty cycle. Add a configurable delay between
configuring the PWM and enabling the backlight regulator to account
for this.

Signed-off-by: Lothar Waßmann <redacted>
---
 .../bindings/leds/backlight/pwm-backlight.txt      |  4 ++++
 drivers/video/backlight/pwm_bl.c                   | 22 +++++++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt
index 764db86..95594c3 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])
+  - turn-on-delay-ms: delay in milliseconds between configuring the PWM
+             and switching PWM on. This may be required to eliminate
+             flicker when switching the PWM on after it has been
+             disabled.

The subject talks about turning on the backlight regulator, but this
only talks about the PWM.

From my understanding "switching PWM on" = enabling the regulator.

I don't see any disparity here.  Or am I missing something?

The delay is from (re-)enabling the PWM (turning it on) to switching
backlight power on. That sounds like 2 different things to me.

Rob