From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933541Ab3LERk2 (ORCPT ); Thu, 5 Dec 2013 12:40:28 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:45178 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933071Ab3LERkY (ORCPT ); Thu, 5 Dec 2013 12:40:24 -0500 Message-ID: <52A0BA85.4020201@wwwdotorg.org> Date: Thu, 05 Dec 2013 10:40:21 -0700 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Stefan Agner CC: thierry.reding@gmail.com, dev@lynxeye.de, lee.jones@linaro.org, lgirdwood@gmail.com, broonie@kernel.org, kai.poggensee@avionic-design.de, sameo@linux.intel.com, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/3] mfd: tps6586x: add version detection References: <77384d24810d9a22fc04cad6f7468f54a9cbaafe.1386108712.git.stefan@agner.ch> <52A0B2AF.60803@wwwdotorg.org> In-Reply-To: X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/05/2013 10:43 AM, Stefan Agner wrote: > Am 2013-12-05 18:06, schrieb Stephen Warren: > >>> @@ -493,13 +527,12 @@ static int tps6586x_i2c_probe(struct i2c_client *client, >>> return -EIO; >>> } >>> >>> - dev_info(&client->dev, "VERSIONCRC is %02x\n", ret); >>> - >>> tps6586x = devm_kzalloc(&client->dev, sizeof(*tps6586x), GFP_KERNEL); >>> - if (tps6586x == NULL) { >>> - dev_err(&client->dev, "memory for tps6586x alloc failed\n"); >>> + if (!tps6586x) >>> return -ENOMEM; >>> - } >>> + >>> + tps6586x->version = ret; >> >> I have to say, I dislike this version of the patch. Separating the >> reading of the version register from the assignment to tps6586x->version >> doesn't make any sense, especially given that the version value is >> stored in a variable named "ret"; that name isn't remotely related to >> what's stored there. What if someone comes along later and adds more >> code that assigns to ret between where it's repurposed for the version >> value and where it's assigned to tps6586x->version? It'd be extremely >> difficult for a patch reviewer to spot that given the limited context in >> a diff, and quite non-obvious to the person changing the code too.. > > The value comes from the return value of i2c_smbus_read_byte_data. If > the value is below zero its an EIO error. > > I could add a variable "version", but for me it felt strange because we > check if version is below zero. This feels like its a wrong version > rather than a transmit error. So I would prefer ret over version. But I > agree, when one just reads the patch, its not obvious what exactly > happens. In my opinion, using a variable named "version" here would be preferable. Testing that against <0 is just the way the I2C API works, so the same argument could be applied to any I2C access.