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,URIBL_BLOCKED,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 9987AC43381 for ; Mon, 1 Apr 2019 18:38:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6598E20896 for ; Mon, 1 Apr 2019 18:38:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728918AbfDASiy (ORCPT ); Mon, 1 Apr 2019 14:38:54 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:54167 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728784AbfDASix (ORCPT ); Mon, 1 Apr 2019 14:38:53 -0400 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 1hB1pY-00030r-69; Mon, 01 Apr 2019 20:38:48 +0200 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1hB1pX-0007sB-Gf; Mon, 01 Apr 2019 20:38:47 +0200 Date: Mon, 1 Apr 2019 20:38:47 +0200 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Martin Blumenstingl Cc: thierry.reding@gmail.com, linux-pwm@vger.kernel.org, linux-amlogic@lists.infradead.org, narmstrong@baylibre.com, jbrunet@baylibre.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, bichao.zheng@amlogic.com Subject: Re: [PATCH 1/2] pwm: meson: consider 128 a valid pre-divider Message-ID: <20190401183847.7xhlgff63cvlzz2h@pengutronix.de> References: <20190401181817.11999-1-martin.blumenstingl@googlemail.com> <20190401181817.11999-2-martin.blumenstingl@googlemail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190401181817.11999-2-martin.blumenstingl@googlemail.com> 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 Hello Martin, On Mon, Apr 01, 2019 at 08:18:16PM +0200, Martin Blumenstingl wrote: > diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c > index f6e738ad7bd9..4b708c1fcb1d 100644 > --- a/drivers/pwm/pwm-meson.c > +++ b/drivers/pwm/pwm-meson.c > @@ -188,7 +188,7 @@ static int meson_pwm_calc(struct meson_pwm *meson, > do_div(fin_ps, fin_freq); > > /* Calc pre_div with the period */ > - for (pre_div = 0; pre_div < MISC_CLK_DIV_MASK; pre_div++) { > + for (pre_div = 0; pre_div <= MISC_CLK_DIV_MASK; pre_div++) { > cnt = DIV_ROUND_CLOSEST_ULL((u64)period * 1000, > fin_ps * (pre_div + 1)); > dev_dbg(meson->chip.dev, "fin_ps=%llu pre_div=%u cnt=%u\n", You could even calculate pre_div without the loop. Something like: u64 pre_div = (u64)period * rate; do_div_round_up(pre_div, NSEC_PER_SEC * 0xffff); pre_div--; (I didn't check rounding and maybe its off by one and ...) This would also get rid of the strange 1000 that is currently used in the calculation without a real benefit (unless I missed something). Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |