From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v4 2/7] dt-bindings: ti-lmu: Modify dt bindings for the LM3697 Date: Fri, 26 Oct 2018 10:30:37 +0200 Message-ID: <20181026083037.GA19434@amd> References: <20181023170623.31820-1-dmurphy@ti.com> <20181023170623.31820-2-dmurphy@ti.com> <20181024090421.GB24997@amd> <20181024145434.GC9327@bogus> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="5mCyUwZo2JvN/JJP" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Jacek Anaszewski Cc: Dan Murphy , Rob Herring , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, lee.jones@linaro.org, tony@atomide.com List-Id: linux-leds@vger.kernel.org --5mCyUwZo2JvN/JJP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > >>>>> +Optional child properties: > >>>>> + - runtime-ramp-up-msec: Current ramping from one brightness level= to > >>>>> + the a higher brightness level. > >>>>> + Range from 2048 us - 117.44 s > This is this problem with the Device Tree's scope of responsibility. > It is defined as a means for "describing the hardware", but often > this rule is abused by the properties that fall into "configuration" > category. E.g. default-state, retain-state-suspended from leds-gpio.txt > or linux-default-trigger from common LED bindings. I always assumed that ramp-up time is there because hardware (power supply?) can not handle "too fast" switching. Missing capacitors or something. If so, this needs to be in device tree. If not, it indeed does not belong to device tree. > In some cases this is justified. The question is whether it is something > that necessarily needs to be configured on driver probing? If not, then > I'd go for sysfs interface. While this would be useful for hardware accelerated patterns, I doubt we want to make it configurable without that support. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --5mCyUwZo2JvN/JJP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlvS0K0ACgkQMOfwapXb+vIyNwCeK2RsHd75QVAKceaWGKzf+yBd iaYAnjGeD0tqO06hau4IIW2z0QdfLLoD =hzIb -----END PGP SIGNATURE----- --5mCyUwZo2JvN/JJP--