Re: [PATCH v12 2/2] iio: accel: Add driver support for ADXL355

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 11 Aug 2021 13:00:27 +0530
Puranjay Mohan <puranjay12@gmail.com> wrote:

> ADXL355 is a 3-axis MEMS Accelerometer. It offers low noise density,
> low 0g offset drift, low power with selectable measurement ranges.
> It also features programmable high-pass and low-pass filters.
> 
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/adxl354_adxl355.pdf
> Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Hi Puranjay,

I took one last look at this so I can apply it without looking again assuming
the dt review is fine.  Noticed one issue with error handling, but I can tidy
that up whilst applying assuming you aren't doing a v13 for some other reason.
If you are please incorporate these changes as well.

Thanks,

Jonathan


...

> +
> +static int adxl355_set_odr(struct adxl355_data *data,
> +			   enum adxl355_odr odr)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&data->lock);
> +
> +	if (data->odr == odr)
> +		goto out_unlock;
> +
> +	ret = adxl355_set_op_mode(data, ADXL355_STANDBY);
> +	if (ret < 0)
> +		goto out_unlock;
> +
> +	ret = regmap_update_bits(data->regmap, ADXL355_FILTER_REG,
> +				 ADXL355_FILTER_ODR_MSK,
> +				 FIELD_PREP(ADXL355_FILTER_ODR_MSK, odr));
> +	if (ret < 0)
> +		goto out_unlock;
> +
> +	data->odr = odr;
> +	adxl355_fill_3db_frequency_table(data);
> +
> +out_unlock:
> +	ret = adxl355_set_op_mode(data, ADXL355_MEASUREMENT);

As below, we should do this because it risks returning success when a failure
actually occured.  Again, unless you are respinning for some other reason I'll
add the logic whilst applying.

> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
> +static int adxl355_set_hpf_3db(struct adxl355_data *data,
> +			       enum adxl355_hpf_3db hpf)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&data->lock);
> +
> +	if (data->hpf_3db == hpf)
> +		goto unlock;
> +
> +	ret = adxl355_set_op_mode(data, ADXL355_STANDBY);
> +	if (ret < 0)
> +		goto set_opmode_unlock;
> +
> +	ret = regmap_update_bits(data->regmap, ADXL355_FILTER_REG,
> +				 ADXL355_FILTER_HPF_MSK,
> +				 FIELD_PREP(ADXL355_FILTER_HPF_MSK, hpf));
> +	if (!ret)
> +		data->hpf_3db = hpf;
> +
> +set_opmode_unlock:
> +	ret = adxl355_set_op_mode(data, ADXL355_MEASUREMENT);

We can't do this as it might potentially eat an error that meant the regmap
update didn't occur.  To avoid that a little dance is needed using a second
return value and we only set ret = ret2 if ret == 0

Alternatively we just have a separate error handling path which doesn't set
ret for the adxl355_set_op_mode(). I'll probably go with that as it's more
code but easier to read.



> +unlock:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +

...

> +static int adxl355_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct adxl355_data *data = iio_priv(indio_dev);
> +	int odr_idx, hpf_idx, calibbias;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		odr_idx = adxl355_find_match(adxl355_odr_table,
> +					     ARRAY_SIZE(adxl355_odr_table),
> +					     val, val2);
> +		if (odr_idx < 0)
> +			return odr_idx;
> +
> +		return adxl355_set_odr(data, odr_idx);
> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> +		hpf_idx = adxl355_find_match(data->adxl355_hpf_3db_table,
> +					ARRAY_SIZE(data->adxl355_hpf_3db_table),

Mixing different indentation styles isn't very nice for readability. 
I'll tweak this whilst applying.

> +					     val, val2);
> +		if (hpf_idx < 0)
> +			return hpf_idx;
> +
> +		return adxl355_set_hpf_3db(data, hpf_idx);
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		calibbias = clamp_t(int, val, S16_MIN, S16_MAX);
> +
> +		return adxl355_set_calibbias(data, chan->address, calibbias);
> +	default:
> +		return -EINVAL;
> +	}
> +}
...