From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752831AbdJ0OiY (ORCPT ); Fri, 27 Oct 2017 10:38:24 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:43827 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751266AbdJ0OiN (ORCPT ); Fri, 27 Oct 2017 10:38:13 -0400 X-Google-Smtp-Source: ABhQp+TN90ouVBYcl9w3IK5bYlbkYyDv0ZY2WHeAL7Ucunu6UcW33W6PXu12a7wNp612YBEEzByfVA== Date: Fri, 27 Oct 2017 09:38:11 -0500 From: Rob Herring To: Lothar =?iso-8859-1?Q?Wa=DFmann?= Cc: Bartlomiej Zolnierkiewicz , Daniel Thompson , Jacek Anaszewski , Jingoo Han , Lee Jones , 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 Subject: Re: [PATCH 2/2] backlight: pwm_bl: add configurable delay between re-enabling PWM and switching backlight power on Message-ID: <20171027140307.x7mtgvy5py7l5nqf@rob-hp-laptop> References: <1509022186-19636-1-git-send-email-LW@KARO-electronics.de> <1509022186-19636-4-git-send-email-LW@KARO-electronics.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1509022186-19636-4-git-send-email-LW@KARO-electronics.de> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > > [0]: Documentation/devicetree/bindings/pwm/pwm.txt > [1]: Documentation/devicetree/bindings/gpio/gpio.txt