Re: [PATCH 2/2] iio: magnetometer: Add driver support for PNI RM3100

[Phil Reid]

On 25/09/2018 9:30 PM, Jonathan Cameron wrote:
> > +static irqreturn_t rm3100_trigger_handler(int irq, void *p)
> > +{
> > +	struct iio_poll_func *pf = p;
> > +	struct iio_dev *indio_dev = pf->indio_dev;
> > +	struct rm3100_data *data = iio_priv(indio_dev);
> > +	struct regmap *regmap = data->regmap;
> > +	u8 buffer[9];
> > +	int ret;
> > +	int i;
> > +
> > +	mutex_lock(&data->lock);
> > +	ret = rm3100_wait_measurement(data);
> > +	if (ret < 0) {
> > +		mutex_unlock(&data->lock);
> > +		goto done;
> > +	}
> > +
> > +	ret = regmap_bulk_read(regmap, RM3100_REG_MX2, buffer, sizeof(buffer));
> > +	mutex_unlock(&data->lock);
> > +	if (ret < 0)
> > +		goto done;
> > +
> > +	/* Convert XXXYYYZZZxxx to XXXxYYYxZZZx. x for padding. */
> > +	for (i = 0; i < 3; i++)
> > +		memcpy(data->buffer + i * 4, buffer + i * 3, 3);
> Firstly X doesn't need copying.
> Secondly the copy of Y actually overwrites the value of Z
> XXXYYYZZZxxx
> XXXxYYYZZxxx
> XXXxYYYxYZZx
>
> I think...
>
> > +
> > +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> > +			iio_get_time_ns(indio_dev));

memcpy target is a different buffer so should be ok.

But that raises the question of does it need to be?
'buffer' could be 12 bytes long and just shuffle Z then Y.
Do the unused bytes need to be zeroed? or does libiio mask them anyway?



--
Regards
Phil Reid