From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFFAAC4360C for ; Mon, 12 Apr 2021 16:40:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 826FF61025 for ; Mon, 12 Apr 2021 16:40:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244672AbhDLQkc (ORCPT ); Mon, 12 Apr 2021 12:40:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244177AbhDLQc7 (ORCPT ); Mon, 12 Apr 2021 12:32:59 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14F1FC06135A for ; Mon, 12 Apr 2021 09:27:31 -0700 (PDT) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lVzPI-0002Jm-Hm; Mon, 12 Apr 2021 18:27:24 +0200 Received: from ukl by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lVzPH-0001ZI-Vk; Mon, 12 Apr 2021 18:27:23 +0200 Date: Mon, 12 Apr 2021 18:27:23 +0200 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Clemens Gruber Cc: linux-pwm@vger.kernel.org, Thierry Reding , Sven Van Asbroeck , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Rob Herring Subject: Re: [PATCH v8 4/8] dt-bindings: pwm: Support new PWM_USAGE_POWER flag Message-ID: <20210412162723.7hlhgqp6wlfbkeky@pengutronix.de> References: <20210412132745.76609-1-clemens.gruber@pqgruber.com> <20210412132745.76609-4-clemens.gruber@pqgruber.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="xlhucg6eoih6yebb" Content-Disposition: inline In-Reply-To: <20210412132745.76609-4-clemens.gruber@pqgruber.com> X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --xlhucg6eoih6yebb Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 12, 2021 at 03:27:41PM +0200, Clemens Gruber wrote: > Add the flag and corresponding documentation for PWM_USAGE_POWER. My concern here in the previous round was that PWM_USAGE_POWER isn't a name that intuitively suggests its semantic. Do you disagree? > Cc: Rob Herring > Signed-off-by: Clemens Gruber > --- > Documentation/devicetree/bindings/pwm/pwm.txt | 3 +++ > include/dt-bindings/pwm/pwm.h | 1 + > 2 files changed, 4 insertions(+) >=20 > diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentatio= n/devicetree/bindings/pwm/pwm.txt > index 084886bd721e..fe3a28f887c0 100644 > --- a/Documentation/devicetree/bindings/pwm/pwm.txt > +++ b/Documentation/devicetree/bindings/pwm/pwm.txt > @@ -46,6 +46,9 @@ period in nanoseconds. > Optionally, the pwm-specifier can encode a number of flags (defined in > ) in a third cell: > - PWM_POLARITY_INVERTED: invert the PWM signal polarity > +- PWM_USAGE_POWER: Only care about the power output of the signal. This > + allows drivers (if supported) to optimize the signals, for example to > + improve EMI and reduce current spikes. IMHO there are too many open questions about which freedom this gives to the lowlevel driver. If the consumer requests .duty_cycle =3D 25ns + =2Eperiod =3D 100ns, can the driver provide .duty_cycle =3D 25s + .period = =3D 100s which nominally has the same power output? Let's not introduce more ambiguity than there already is. This is a NAck. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | https://www.pengutronix.de/ | --xlhucg6eoih6yebb Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAmB0dOgACgkQwfwUeK3K 7AkyoAgAj56WHSz3mbbQpQYJfzLAgaVxZH4sopRLrKgguHa/mEHhlxerTk239Pit 0ePi/frDOR6+xWdP96WxYTIdivJ3+Tddpqgt+L6d9yu8S4DSRZwtrpU+3/DGjAhm TsTjV0Sj/xMb81vBwizQjFOyopsKEXHujAE4Y2+8CwtR7ns2m0L43hifWD8eaJKB WapPTzjH0CYZHOr0t6EbX0JQVqYNObZywx/1NRyyjjy8ypJ1Vt52mpuw35tmGL8r sC5Ur2byGV7thCkewB6ufCy6Ks50AIzdktrgaLMjOE2c8SL2Gg1HjWov1heOVUWq qNrgmb3zkNOEr4spJpdNiAbbLoQsRA== =V9Pw -----END PGP SIGNATURE----- --xlhucg6eoih6yebb--