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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D10AC433EF for ; Wed, 9 Feb 2022 22:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235363AbiBIWVp convert rfc822-to-8bit (ORCPT ); Wed, 9 Feb 2022 17:21:45 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:49660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235335AbiBIWVi (ORCPT ); Wed, 9 Feb 2022 17:21:38 -0500 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8BCF1C0F8699 for ; Wed, 9 Feb 2022 14:21:40 -0800 (PST) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-66-G1dgHlBaNBupzuHAnSEDBA-1; Wed, 09 Feb 2022 22:21:37 +0000 X-MC-Unique: G1dgHlBaNBupzuHAnSEDBA-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.28; Wed, 9 Feb 2022 22:21:36 +0000 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.028; Wed, 9 Feb 2022 22:21:35 +0000 From: David Laight To: 'Qing Wang' , Abel Vesa , "Michael Turquette" , Stephen Boyd , "Shawn Guo" , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , "linux-clk@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] clk: imx: use div64_u64() instead of do_div() Thread-Topic: [PATCH] clk: imx: use div64_u64() instead of do_div() Thread-Index: AQHYHZBjXPxrJKPUzEuGCK2WjoSvgayLy2mg Date: Wed, 9 Feb 2022 22:21:35 +0000 Message-ID: <4f0336b0217f4e7fa9a1a7aa044ee4fe@AcuMS.aculab.com> References: <1644395819-3791-1-git-send-email-wangqing@vivo.com> In-Reply-To: <1644395819-3791-1-git-send-email-wangqing@vivo.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qing Wang > Sent: 09 February 2022 08:37 > > From: Wang Qing > > do_div() does a 64-by-32 division. > When the divisor is u64, do_div() truncates it to 32 bits, this means it > can test non-zero and be truncated to zero for division. What is the domain of parent_rate? Unless it can exceed 2^32 do_div() is correct. Ignore checkpatch. > > fix do_div.cocci warning: > WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead. > > Signed-off-by: Wang Qing > --- > drivers/clk/imx/clk-frac-pll.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/clk/imx/clk-frac-pll.c b/drivers/clk/imx/clk-frac-pll.c > index c703056..90b25e3 > --- a/drivers/clk/imx/clk-frac-pll.c > +++ b/drivers/clk/imx/clk-frac-pll.c > @@ -129,11 +129,11 @@ static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate, > parent_rate *= 8; > rate *= 2; > temp64 = rate; > - do_div(temp64, parent_rate); > + div64_u64(temp64, parent_rate); > divfi = temp64; > temp64 = rate - divfi * parent_rate; > temp64 *= PLL_FRAC_DENOM; > - do_div(temp64, parent_rate); > + div64_u64(temp64, parent_rate); > divff = temp64; > > temp64 = parent_rate; > -- > 2.7.4 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)