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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 9A339C43381 for ; Thu, 14 Feb 2019 15:59:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 72416218EA for ; Thu, 14 Feb 2019 15:59:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502467AbfBNP7L (ORCPT ); Thu, 14 Feb 2019 10:59:11 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:42669 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392172AbfBNP7K (ORCPT ); Thu, 14 Feb 2019 10:59:10 -0500 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1guJPk-0005T9-Uj; Thu, 14 Feb 2019 16:59:04 +0100 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1guJPj-0004KM-Rg; Thu, 14 Feb 2019 16:59:04 +0100 Date: Thu, 14 Feb 2019 16:59:03 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Thierry Reding Cc: Yash Shah , palmer@sifive.com, linux-pwm@vger.kernel.org, linux-riscv@lists.infradead.org, robh+dt@kernel.org, mark.rutland@arm.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, sachin.ghadi@sifive.com, paul.walmsley@sifive.com Subject: Re: [PATCH v5 2/2] pwm: sifive: Add a driver for SiFive SoC PWM Message-ID: <20190214155903.7h3b7v3nbhj57uy2@pengutronix.de> References: <1548762199-7065-1-git-send-email-yash.shah@sifive.com> <1548762199-7065-3-git-send-email-yash.shah@sifive.com> <20190207101657.rfzcq6xdv6ocvubg@pengutronix.de> <20190213123703.GE647@ulmo> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190213123703.GE647@ulmo> User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 13, 2019 at 01:37:03PM +0100, Thierry Reding wrote: > On Thu, Feb 07, 2019 at 11:16:57AM +0100, Uwe Kleine-König wrote: > > On Tue, Jan 29, 2019 at 05:13:19PM +0530, Yash Shah wrote: > [...] > > > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > [...] > > > + writel(val, pwm->regs + PWM_SIFIVE_PWMCFG); > > > + > > > + writel(frac, pwm->regs + PWM_SIFIVE_PWMCMP0 + dev->hwpwm * SIZE_PWMCMP); > > > + > > > + val &= ~(1 << PWM_SIFIVE_PWMCFG_DEGLITCH); > > > + writel(val, pwm->regs + PWM_SIFIVE_PWMCFG); > > > + > > > + pwm_sifive_get_state(chip, dev, state); > > > > Thierry: This changes the pwm_state. Is this how this should be done? > > Yes, I think that's fine. The PWM state should always reflect the > current hardware state. If the configuration that we program does not > reflect the state that was requested, that should be reflected in the > PWM state. I'm not sure you blessed what is really done here. If I do: state.duty_cycle = state.period; pwm_apply_state(pwm, &state); the call in question doesn't only result in pwm->state.duty_cycle < pwm->state.period, but it also corrects my local state variable (i.e. I have state.duty_cycle < state.period afterwards). Is this what you thought to be fine? Also note that v6 dropped that call because of my doubts. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |