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=-10.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 95BD7C4338F for ; Sat, 31 Jul 2021 18:06:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 702F560FE7 for ; Sat, 31 Jul 2021 18:06:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231419AbhGaSGg (ORCPT ); Sat, 31 Jul 2021 14:06:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229694AbhGaSGf (ORCPT ); Sat, 31 Jul 2021 14:06:35 -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 2C980C0613CF; Sat, 31 Jul 2021 11:06:29 -0700 (PDT) Received: by mail-ot1-x333.google.com with SMTP id f20-20020a9d6c140000b02904bb9756274cso1292464otq.6; Sat, 31 Jul 2021 11:06:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=kkXChpviXo2g9C3NzdUsOIvhQv77EXpLWm7556u8OXs=; b=DoQHLhm2JCFEZfnF6AjQv337TkzhQPxSJAJM+bdjchfgrjjYSD/RTPc+oS4O46vOmf vYNrYIT9HEdZnSVFLntxUapr/b/aq6XxwqMgkzAW8QbYlls3nA4Paf/mIky/dWeZ4Y+d b5enySD6jWCrPtNM1/6QogzrnRUQ8wiTrhI9FFUEwZYJuZS5kUKIRwVJC8RP8pHpP08i qYf+yXYYBlNL+e+cqQ3sZlDItbDplb00QLJbTCBZHC2kcMb0N/JgjqTaM7FtxQMFNBdj nusaaC9MU9S6PSOqHSkZfUy5SUehntKMbUaQGsNm3FfQjjlJBp7WyQk0swIWn/ZW9hY0 lDmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; 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=kkXChpviXo2g9C3NzdUsOIvhQv77EXpLWm7556u8OXs=; b=sOHQFZi5JekXUKMCXrF7/CvBWs+Xe5ZDB8vshB+hTgls7DU0HSGqsGauIsfe3gQ5bm MLMv6Gs+hPIA1VSrVQA6iiBf9HxZD7cQtd352TQu2yeiXbTFQlqnRw0GDE/qKScfhQG9 mc2rgtAoqcYsBDKOflpgIQ6FmvQwAShuLhRQlcanddQ/csVrjRtc6/ja8MLdNEzqL4FH T5gMPZFH1dBPrZLJJ6iesxDqOb1G6UneKkKWxb3Ci1Mr+5mAmNdwF3fWc/kUFYYpoxL1 ChIf99NMBbsPEERk+LUvw2Jhf5cjmwQvVqpLPIBI+fJqF6bmXMJzhE/jhL6Dr5VEtsiL cnwA== X-Gm-Message-State: AOAM530zfv5Y7TLmw5JI+Q/y8U+lmSSxkAsoD0ULHOhH7/TST6TrS13/ M4ltZznsxqHYqQBJEzYV11E= X-Google-Smtp-Source: ABdhPJyQpO9WO+JOAej5L+nwDlJDHRdm1PxLRK29l8JeaSGW35l4oC0po0pqlC4DTuuDNyCS6lmrdg== X-Received: by 2002:a05:6830:2452:: with SMTP id x18mr6326465otr.196.1627754788583; Sat, 31 Jul 2021 11:06:28 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id r16sm970334otu.26.2021.07.31.11.06.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 31 Jul 2021 11:06:27 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH 2/2] iio: chemical: Add driver support for sgp40 To: Jonathan Cameron , Andreas Klinger Cc: devicetree@vger.kernel.org, linux-iio@vger.kernel.org, Rob Herring , Jonathan Cameron , Jiri Kosina , Chris Packham , Slawomir Stepien , Krzysztof Kozlowski , Alexandre Belloni , Vadim Pasternak , Alexandru Ardelean , linux-kernel@vger.kernel.org, Lars-Peter Clausen , Tomasz Duszynski References: <20210727163517.GA3468@arbad> <20210731173928.08d6812f@jic23-huawei> From: Guenter Roeck Message-ID: <42e31edc-445c-06ac-dd3a-80db1b439996@roeck-us.net> Date: Sat, 31 Jul 2021 11:06:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210731173928.08d6812f@jic23-huawei> 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 7/31/21 9:39 AM, Jonathan Cameron wrote: > On Tue, 27 Jul 2021 18:35:19 +0200 > Andreas Klinger wrote: > >> sgp40 is a gas sensor used for measuring the air quality. >> >> This driver is reading the raw resistance value which can be passed to >> a userspace algorithm for further calculation. >> >> The raw value is also used to calculate an estimated absolute voc index >> in the range from 0 to 500. For this purpose the raw_mean value of the >> resistance for which the index value is 250 might be set up as a >> calibration step. >> >> Compensation of relative humidity and temperature is supported and can >> be used by writing to device attributes of the driver. >> >> There is a predecesor sensor type (sgp30) already existing. This driver >> module was not extended because the new sensor is quite different in its >> i2c telegrams. >> >> Signed-off-by: Andreas Klinger > > Hi Andreas, > > Non standard ABI in here, so we are missing documentation in Documentation/ABI/testing/sysfs-bus-iio-* > > Otherwise a few suggestions inline. > > Thanks, > > Jonathan > > >> --- [ ... ] >> +static int sgp40_read_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, int *val, >> + int *val2, long mask) >> +{ >> + struct sgp40_data *data = iio_priv(indio_dev); >> + int ret; >> + u16 raw; >> + int voc; >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_RAW: >> + mutex_lock(&data->lock); >> + ret = sgp40_measure_raw(data, &raw); >> + if (ret) { >> + mutex_unlock(&data->lock); >> + return ret; >> + } >> + *val = raw; >> + ret = IIO_VAL_INT; >> + mutex_unlock(&data->lock); >> + break; >> + case IIO_CHAN_INFO_PROCESSED: >> + mutex_lock(&data->lock); >> + ret = sgp40_measure_raw(data, &raw); >> + if (ret) { >> + mutex_unlock(&data->lock); >> + return ret; >> + } >> + ret = sgp40_calc_voc(data, raw, &voc); >> + if (ret) { >> + mutex_unlock(&data->lock); >> + return ret; >> + } >> + *val = voc; >> + ret = IIO_VAL_INT; >> + mutex_unlock(&data->lock); > > You are holding the lock longer than needed - it would be good > to reduce this, hopefully removing the need for unlocking separately > in each of the error paths. > >> + break; >> + default: >> + return -EINVAL; >> + } >> + >> + return ret; > > Drop this as you can't get here. > Are you sure ? I see several "break;" above. Guenter