[lkml]   [2013]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v4 1/3] mfd: tps6586x: add version detection
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

In v2, I moved the i2c_smbus_read_byte_data function call after the
allocation, so it was more obvious for the reader. But then, as Thierry
Reding pointed out, not moving it is an optimization: In case reading
fails, we don't allocate memory first.

 \ /
  Last update: 2013-12-05 20:01    [W:0.112 / U:0.332 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site