Re: [PATCH v2 3/4] hwmon: Add support for Amphenol ChipCap 2

[Guenter Roeck]

On 11/9/23 00:52, Krzysztof Kozlowski wrote:
> On 08/11/2023 16:37, Javier Carrasco wrote:
> > The Amphenol ChipCap 2 is a capacitive polymer humidity and temperature
> > sensor with an integrated EEPROM and minimum/maximum humidity alarms.
> >
> > All device variants offer an I2C interface and depending on the part
> > number, two different output modes:
> > - CC2D: digital output
> > - CC2A: analog (PDM) output
> >
> > This driver adds support for the digital variant (CC2D part numbers),
> > which is also divided into two subfamilies [1]:
> > - CC2DXX: non-sleep measurement mode
> > - CC2DXXS: sleep measurement mode
>
> ...
>
> > +
> > +static int cc2_probe(struct i2c_client *client)
> > +{
> > +	struct cc2_data *data;
> > +	struct device *dev = &client->dev;
> > +	enum cc2_ids chip;
> > +	int ret;
> > +
> > +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> > +		return -EOPNOTSUPP;
> > +
> > +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +	if (!data)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, data);
> > +
> > +	mutex_init(&data->i2c_lock);
> > +	mutex_init(&data->alarm_lock);
> > +
> > +	data->client = client;
> > +
> > +	if (client->dev.of_node)
> > +		chip = (uintptr_t)of_device_get_match_data(&client->dev);
> > +	else
> > +		chip = i2c_match_id(cc2_id, client)->driver_data;
> > +
> > +	data->config = &cc2_config[chip];
> > +
> > +	ret = cc2_request_ready_irq(data, dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	data->regulator = devm_regulator_get_optional(dev, "vdd");
> > +	if (!IS_ERR(data->regulator)) {
> > +		ret = cc2_retrive_alarm_config(data);

fwiw, s/retrive/retrieve/g

> > +		if (ret)
> > +			goto cleanup;
> > +	} else {
> > +		/* No access to EEPROM without regulator: no alarm control */
> > +		goto dev_register;
>
> Nothing improved here.
>
> Do not send new version of patchset before discussion finishes.

This driver will take a while to review due to its complexity.

As for the code above: Error handling goes first. Something like
the above, where the error case is just a goto, is unacceptable and
just increases indentation level for the other code and makes it
more difficult to read. Also, the above code _will_ have to handle
error cases other than -ENODEV. Besides deferred probe, it is
completely inappropriate to ignore -EINVAL or -ENOMEM or any other
error codes other than -ENODEV.

> > +	}
> > +
> > +	ret = cc2_request_alarm_irqs(data, dev);
> > +	if (ret)
> > +		goto cleanup;
> > +
> > +dev_register:
> > +	data->hwmon = devm_hwmon_device_register_with_info(dev, client->name,
> > +							   data, &cc2_chip_info,
> > +							   NULL);
> > +	if (IS_ERR(data->hwmon)) {
> > +		ret = PTR_ERR(data->hwmon);
> > +		goto cleanup;
> > +	}
> > +
> > +	return 0;
> > +
> > +cleanup:
> > +	if (cc2_disable(data))
> > +		dev_dbg(dev, "Failed to disable device");
> > +
> > +	return dev_err_probe(dev, ret,
> > +			     "Unable to register hwmon device\n");
>
> Drop or move to each error path.
This actually follows Documentation/process/coding-style.rst, chapter 7
(Centralized exiting of functions).

Guenter