From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH 2/2] backlight: pwm_bl: add configurable delay between re-enabling PWM and switching backlight power on Date: Mon, 30 Oct 2017 10:33:34 +0000 Message-ID: <20171030103334.75ii247j6owrnrdb@dell> References: <1509022186-19636-1-git-send-email-LW@KARO-electronics.de> <1509022186-19636-4-git-send-email-LW@KARO-electronics.de> <20171027140307.x7mtgvy5py7l5nqf@rob-hp-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20171027140307.x7mtgvy5py7l5nqf@rob-hp-laptop> Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Lothar =?iso-8859-1?Q?Wa=DFmann?= , Bartlomiej Zolnierkiewicz , Daniel Thompson , Jacek Anaszewski , Jingoo Han , Mark Rutland , Pavel Machek , Richard Purdie , Thierry Reding , devicetree@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, linux-pwm@vger.kernel.org List-Id: devicetree@vger.kernel.org On Fri, 27 Oct 2017, Rob Herring wrote: > On Thu, Oct 26, 2017 at 02:49:46PM +0200, Lothar Waßmann wrote: > > 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 > > --- > > .../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? > > [0]: Documentation/devicetree/bindings/pwm/pwm.txt > > [1]: Documentation/devicetree/bindings/gpio/gpio.txt -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog