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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6458C433FE for ; Mon, 1 Nov 2021 03:48:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE88A60FE8 for ; Mon, 1 Nov 2021 03:48:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230395AbhKADup (ORCPT ); Sun, 31 Oct 2021 23:50:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230222AbhKADun (ORCPT ); Sun, 31 Oct 2021 23:50:43 -0400 Received: from mail-ot1-x333.google.com (mail-ot1-x333.google.com [IPv6:2607:f8b0:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2170BC061714; Sun, 31 Oct 2021 20:48:11 -0700 (PDT) Received: by mail-ot1-x333.google.com with SMTP id v2-20020a05683018c200b0054e3acddd91so23551637ote.8; Sun, 31 Oct 2021 20:48:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=dSMSdJzsSo0hXmRoiI8+pJHJkW+iwLpzQ5iUUQzYzcg=; b=kpzDjCz6aWw7ruDUm2P0xUDUZbzCv4ujV8tBQ+kNfJTj3xXfc/2h20isqd0yR8bGk+ slKMEx+ZDRejcG3g2osOcq9QgY+Cf4oUG2u4WTX8/N7rFbtR2jjo+mqUXPjYR9bpth7r 10lfxDKY4v/CDDeZyOBcSaeyXzdITuA194RW6Seg+SRdtmLX1jNEW74xKGGHTOT1IpJA yodA5PhxvU20m5yRMFt5hjJ24//dfRnU9i6uM13VDuBoNrB4b+CR5zwpZ/+bALv8cQsj TNTO1ktl4eXVu8JMKiZHn2/If11d2hgSV5zmfqyiv+ConLAVSvsEezLPUBsAepjmeLQd SAYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=dSMSdJzsSo0hXmRoiI8+pJHJkW+iwLpzQ5iUUQzYzcg=; b=BiT9pb4YP+3md7EMYm6UrivEw9br6/adDzQU4lF2DsL+rWMEre2VZF0GT+Bfv3kS9W kXJym3H9RvmMPSmIBUmfFbojCBtkVZ7eH77zps6GwKh0/LFivsXaxXlE0pkJQ1zrsgk+ GucwUm0xaIcmuFppcmDAgsQenguqrNieg0n6E20uXjWLhDUETQ/XI1lEiJ+vC5PMOog9 walFIoCjyQBUFzXQWhRVDzmrFKJLIGOMzYrKefeO+FW82Rw+bRmKEkp9pRPW3G/H7goq CJLd8IQicuruyfbOJC7mKEkYvyHwkJLlFuUe5+3/MHdAxxJLV7TLAUfk4nsbi1nqJflm G3lg== X-Gm-Message-State: AOAM531z2DfmfaOUym4JsNt0MtvSD7Aej5EeoN8E/qiKGUxQkFDD4wGE NO4aC71RzGNnxl0CnXuiUxAVbiXZ9jU= X-Google-Smtp-Source: ABdhPJy8ZqxMRV8FgxBwfMiNcet12Kj3O0DoVaiMt7WfaidrfQsSt8y9GB41WVsWHj1MLcVOMMhwZg== X-Received: by 2002:a05:6830:43aa:: with SMTP id s42mr1510744otv.13.1635738490389; Sun, 31 Oct 2021 20:48:10 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id r23sm1384074ooh.44.2021.10.31.20.48.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 31 Oct 2021 20:48:09 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH v3 3/3] hwmon: Driver for Texas Instruments INA238 To: Nathan Rossi Cc: linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Nathan Rossi , Jean Delvare , Jonathan Corbet References: <20211028081030.719265-0-nathan@nathanrossi.com> <20211028081030.719265-3-nathan@nathanrossi.com> <7b6764bf-4978-60ec-b1e6-8d59077c3023@roeck-us.net> From: Guenter Roeck Message-ID: <43c17bba-d4bd-1f9d-5034-1f5a9279d751@roeck-us.net> Date: Sun, 31 Oct 2021 20:48:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/31/21 7:20 PM, Nathan Rossi wrote: [ ... ] >>> + >>> + if (attr != hwmon_in_max && attr != hwmon_in_min) >>> + return -EOPNOTSUPP; >>> + >>> + /* convert decimal to register value */ >>> + switch (channel) { >>> + case 0: >>> + /* signed value, clamp to max range +/-163 mV */ >>> + regval = clamp_val(val, -163, 163); >>> + regval = (regval * 1000L * (4 - (int)data->gain + 1)) / >> >> nit: The typecast "(int)" is not needed here. > > Due to the unsigned type of gain, it causes promotion of regval (and > the rest of the numerator) to unsigned long which causes issues with > negative numbers on the divide. It makes more sense for gain to be an > int to begin with, I will change it to int to avoid the need for type > casting. > Are you sure ? I initially thought that as well and wrote a little test program with that expression, but it didn't do the promotion to unsigned. Thanks, Guenter