Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751279AbdGMHkC (ORCPT ); Thu, 13 Jul 2017 03:40:02 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:44405 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750947AbdGMHj6 (ORCPT ); Thu, 13 Jul 2017 03:39:58 -0400 Date: Thu, 13 Jul 2017 09:39:54 +0200 From: Pavel Machek To: Enric Balletbo Serra Cc: Rob Herring , Enric Balletbo i Serra , Thierry Reding , Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz , Richard Purdie , Jacek Anaszewski , Heiko Stuebner , Linux PWM List , "linux-fbdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Guenter Roeck , "open list:ARM/Rockchip SoC..." , huang lin Subject: Re: [PATCH v2 1/4] dt-bindings: pwm-backlight: add pwm-delay-us property Message-ID: <20170713073954.GA1363@amd> References: <20170630112109.13785-1-enric.balletbo@collabora.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Q68bSM7Ycu6FN28Q" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3348 Lines: 90 --Q68bSM7Ycu6FN28Q Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu 2017-07-13 09:22:15, Enric Balletbo Serra wrote: > Rob, >=20 > 2017-07-06 20:23 GMT+02:00 Enric Balletbo Serra : > > Hi Rob, > > > > 2017-07-06 19:07 GMT+02:00 Rob Herring : > >> On Fri, Jun 30, 2017 at 6:21 AM, Enric Balletbo i Serra > >> wrote: > >>> From: huang lin > >>> > >>> 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 > >>> Signed-off-by: Enric Balletbo i Serra > >>> --- > >>> Changes since v1: > >>> - As suggested by Daniel Thompson > >>> - Do not assume power-on delay and power-off delay will be the same > >>> > >>> v1: https://lkml.org/lkml/2017/6/28/219 > >>> > >>> Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt |= 6 ++++++ > >>> 1 file changed, 6 insertions(+) > >>> > >>> diff --git a/Documentation/devicetree/bindings/leds/backlight/pwm-bac= klight.txt b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight= =2Etxt > >>> index 764db86..49b037e 100644 > >>> --- a/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.= txt > >>> +++ b/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.= txt > >>> @@ -17,6 +17,11 @@ Optional properties: > >>> "pwms" property (see PWM binding[0]) > >>> - enable-gpios: contains a single GPIO specifier for the GPIO whic= h enables > >>> and disables the backlight (see GPIO binding[1]) > >>> + - pwm-delay-us: delay between setting an initial (non-zero) PWM va= lue and > >>> + enabling the backlight, and also the delay between= disabling > >>> + the backlight and setting PWM value to 0. > >>> + The 1st cell is the pre-delay in micro seconds. > >>> + The 2nd cell is the post-delay in micro seconds. > >> > >> pre and post imply a time before and after a certain event, but these > >> are for 2 different events. These are more like an enable/on delay and > >> disable/off delay which probably should be separate properties. What > >> happens when we need the opposite sequence or a different sequence? > >> Maybe some panel requires the PWM to be 0 until some time after > >> enabling. > >> >=20 > A second proposal, what do you think? >=20 > - post-pwm-on-delay-us: Delay in us after setting an initial (non-zero)= PWM > and enabling the backlight using GPIO. This says "PWM on", "enable GPIO", "delay". Which is not what you want. --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --Q68bSM7Ycu6FN28Q Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAllnI8oACgkQMOfwapXb+vKDVQCglfZS7dk3+pM2q+67EM4tIyNA rlQAoIsmY4LMRyOX8y8rq3l60f+XaJve =MgV+ -----END PGP SIGNATURE----- --Q68bSM7Ycu6FN28Q--