Re: [PATCH v1 2/3] iio: ltr501: Add interrupt rate control support

[Daniel Baluta <daniel.baluta@gmail.com>]

On Wed, Apr 1, 2015 at 5:55 AM, Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
> Added rate control support for ALS and proximity
> threshold interrupts.
>
> Setting <n> to ALS intr_persist sysfs node would
> generate interrupt whenever ALS data cross either
> upper or lower threshold limits <n> number of times.
> Similarly setting <m> to proximity intr_persist sysfs
> node would genere interrupt whenever proximity data falls
> outside threshold limit <m> number of times.
>

<snip>

> +static ssize_t ltr501_read_intr_prst(struct iio_dev *indio_dev,
> +                                  uintptr_t private,
> +                                  const struct iio_chan_spec *chan,
> +                                  char *buf)
> +{
> +       struct ltr501_data *data = iio_priv(indio_dev);
> +       int ret = -EINVAL;
> +
> +       switch (chan->type) {
> +       case IIO_INTENSITY:
> +               mutex_lock(&data->lock_als);
> +               ret = i2c_smbus_read_byte_data(data->client, LTR501_INTR_PRST);
> +               mutex_unlock(&data->lock_als);

I am not sure I understand why is the mutex needed here? AFAIK I2C transactions
are serialized.

<snip>

> +static const struct iio_chan_spec_ext_info ltr501_ext_info[] = {
> +       {
> +               .name = "intr_persist",
> +               .read = ltr501_read_intr_prst,
> +               .write = ltr501_write_intr_prst,
> +               .shared = IIO_SHARED_BY_TYPE,
> +       },
> +       {},
> +};
> +
Would be nice to standardize persistence attribute (IIO_CHAN_INFO_PERSISTENCE).

thanks,
Daniel.