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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A4851C4332D for ; Thu, 14 Jan 2021 18:06:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69DB723741 for ; Thu, 14 Jan 2021 18:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729458AbhANSFx (ORCPT ); Thu, 14 Jan 2021 13:05:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726743AbhANSFw (ORCPT ); Thu, 14 Jan 2021 13:05:52 -0500 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 67887C061796 for ; Thu, 14 Jan 2021 10:05:12 -0800 (PST) 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 1l06ze-0005bf-3P; Thu, 14 Jan 2021 19:05:10 +0100 Received: from ukl by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1l06zd-0003wT-HD; Thu, 14 Jan 2021 19:05:09 +0100 Date: Thu, 14 Jan 2021 19:05:09 +0100 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Clemens Gruber Cc: Sven Van Asbroeck , Thierry Reding , Linux Kernel Mailing List , linux-pwm@vger.kernel.org Subject: Re: [PATCH v5 2/7] pwm: pca9685: Support hardware readout Message-ID: <20210114180509.j5wcbxuwx4rzfys7@pengutronix.de> References: <20201216125320.5277-1-clemens.gruber@pqgruber.com> <20201216125320.5277-2-clemens.gruber@pqgruber.com> <20210111203532.m3yvq6e5bcpjs7mc@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="j6p2aexwzcoijx25" Content-Disposition: inline In-Reply-To: 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-pwm@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org --j6p2aexwzcoijx25 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello Clemens, On Thu, Jan 14, 2021 at 06:16:22PM +0100, Clemens Gruber wrote: > On Mon, Jan 11, 2021 at 09:35:32PM +0100, Uwe Kleine-K=F6nig wrote: > > My position here is: A consumer should disable a PWM before calling > > pwm_put. The driver should however not enforce this and so should not > > modify the hardware state in .free(). > >=20 > > Also .probe should not change the PWM configuration. >=20 > I see. This would also allow PWMs initialized in the bootloader (e.g. > backlights) to stay on between the bootloader and Linux and avoid > flickering. >=20 > If no one objects, I would then no longer reset period and duty cycles > in the driver (and for our projects, reset them in the bootloader code > to avoid leaving PWMs on after a kernel panic and watchdog reset, etc.) >=20 > And if there is no pre-known state of the registers, we actually need > the .get_state function fully implemented. This sounds right. Thanks Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | https://www.pengutronix.de/ | --j6p2aexwzcoijx25 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAmAAh9IACgkQwfwUeK3K 7AkiRAf9HsjBHUFdx6tf8RgomKLnOSg5mQTjTfN8l5r3rM3YvPFexDA8bEMrCbD9 odIhii9oDJwwaK3MeDe2ox3wiP/fK/7NtOCO2ipDTtBt41VCdyAjJQBHrOQk3MyG tMUSpnc9Ly7ebOJg1wKDl3m9WwBRtyUixnKkh/DzxCw6cQYL/0yc67pYAuk94Yft s/kHzoqmiMoTLaVnOg84nt4j1k2vI7e3PAUA/IbmChOTHTkvU+wo2Wl61rb5Jhus 1AC0uKvsXssHMVk2NSYCB0bdS2HRpTOR6L1uEyDRINqBG6zjiDGHoKQjjzDDjqd9 eG5JusA5ChrNvkqwHsW+oMLZ4GfQDg== =7aIM -----END PGP SIGNATURE----- --j6p2aexwzcoijx25--