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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 A63F7C2BBE2 for ; Fri, 6 Dec 2019 14:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C4DE20706 for ; Fri, 6 Dec 2019 14:37:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PFDgxgxf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726287AbfLFOhH (ORCPT ); Fri, 6 Dec 2019 09:37:07 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:36885 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726195AbfLFOhG (ORCPT ); Fri, 6 Dec 2019 09:37:06 -0500 Received: by mail-pl1-f195.google.com with SMTP id bb5so2805261plb.4; Fri, 06 Dec 2019 06:37:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=MmAJYe9y7hqJDFUyCzbIg+/OBoZV4/dfN8ALgALbljo=; b=PFDgxgxfa1SQfvN602ZGkhQGP+RUlpRbKFPdeHwt1yx2/1QK8DF9XuSXfmlbmGFH3O qdnjDNdPuTVtV3jDzel/MzOUc0ADPf/EZrQDJVSCc+FlKKP/WO1hJawk+sYjb+tp5mq3 fkpyaBZY6P5YQ4/RXNM0BN9xMn63GrqAgPsU5CBo1mUlwVt+pUF1uyQyMQDPe+/seJPo QqE3SwtEf+cZtfGvCVduV/gvw6mE20+J5bTBs1M2BoDfN/RO4vv+OupEtubpY3j7LoYx xziCwRNHPRfT1QxlUOcEOftAzCunpp47VZilf2huVZBnJNvoJBPpRLq808H7MXSuQq1M 3iQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=MmAJYe9y7hqJDFUyCzbIg+/OBoZV4/dfN8ALgALbljo=; b=fVAeNcPmYHjQGV4JpR4jJW8RVWXZzY/SAkW6CgGU/hRnHbR/rtYM89L/TG5bv/jKjS 7qgR8DUPo5ZdWdxSt3KUDyq7/HRrfeFZBspAYVQgtoeE3UlHdNy//Wj8cBNFqXMmyUn7 lgBHw30++IU6QaPE3K6m/kWabAFz6rfdjRXljKcBenchw1i2QlTrGHreQGOFzCajCzH2 pbEvlL0MsE9SAJTC34i2fzPwXnWzyR6+h96qoz6ebWTtYf+jscDBpCK5Q3EvCDysc1p0 HPwWYUwA+jrTxkHNxjaSXR/XQLhVNsbPnRK/LxIvviCD27Lz+h5UdNCxQQrSKa/xH2Lu PB9w== X-Gm-Message-State: APjAAAUobGja8EqZTflDleX4zUBW6IKOoi7pfOx+57gYp2PUxv8McRR4 GCKzbCwZD54r8XrkvZMCg80= X-Google-Smtp-Source: APXvYqxJGdkN7RNKsZLyt14TxInds+wbC8VNpPQfJGJOSwV7v/peQJDCs7D08nXCIJ/B4vPMqxaFrA== X-Received: by 2002:a17:90a:a44:: with SMTP id o62mr15799733pjo.80.1575643025840; Fri, 06 Dec 2019 06:37:05 -0800 (PST) Received: from localhost ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id 186sm16865700pfe.141.2019.12.06.06.37.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 06 Dec 2019 06:37:05 -0800 (PST) Date: Fri, 6 Dec 2019 06:37:03 -0800 From: Guenter Roeck To: Luuk Paulussen Cc: Jean Delvare , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] hwmon: (adt7475) Make volt2reg return same reg as reg2volt input Message-ID: <20191206143703.GA2291@roeck-us.net> References: <20191205225755.GC2532@roeck-us.net> <20191205231659.1301-1-luuk.paulussen@alliedtelesis.co.nz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191205231659.1301-1-luuk.paulussen@alliedtelesis.co.nz> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 06, 2019 at 12:16:59PM +1300, Luuk Paulussen wrote: > reg2volt returns the voltage that matches a given register value. > Converting this back the other way with volt2reg didn't return the same > register value because it used truncation instead of rounding. > > This meant that values read from sysfs could not be written back to sysfs > to set back the same register value. > > With this change, volt2reg will return the same value for every voltage > previously returned by reg2volt (for the set of possible input values) > > Signed-off-by: Luuk Paulussen Applied. Thanks, Guenter > --- > changes in v2: > - remove unnecessary braces. > drivers/hwmon/adt7475.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c > index 6c64d50c9aae..01c2eeb02aa9 100644 > --- a/drivers/hwmon/adt7475.c > +++ b/drivers/hwmon/adt7475.c > @@ -294,9 +294,10 @@ static inline u16 volt2reg(int channel, long volt, u8 bypass_attn) > long reg; > > if (bypass_attn & (1 << channel)) > - reg = (volt * 1024) / 2250; > + reg = DIV_ROUND_CLOSEST(volt * 1024, 2250); > else > - reg = (volt * r[1] * 1024) / ((r[0] + r[1]) * 2250); > + reg = DIV_ROUND_CLOSEST(volt * r[1] * 1024, > + (r[0] + r[1]) * 2250); > return clamp_val(reg, 0, 1023) & (0xff << 2); > } >