From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Thu, 05 Dec 2013 10:40:21 -0700 Subject: [PATCH v4 1/3] mfd: tps6586x: add version detection In-Reply-To: References: <77384d24810d9a22fc04cad6f7468f54a9cbaafe.1386108712.git.stefan@agner.ch> <52A0B2AF.60803@wwwdotorg.org> Message-ID: <52A0BA85.4020201@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.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.