Re: [PATCH v2 3/4] iio: vcnl4000: Export near level property for proximity sensor

Guido Günther
2020-03-17T12:05:42Z

Hi,
On Mon, Mar 16, 2020 at 07:23:01PM +0100, Lars-Peter Clausen wrote:
> On 3/16/20 6:46 PM, Guido Günther wrote:
> > [...]
> > +static ssize_t vcnl4000_read_near_level(struct iio_dev *indio_dev,
> > + uintptr_t priv,
> > + const struct iio_chan_spec *chan,
> > + char *buf)
> > +{
> > + struct vcnl4000_data *data = iio_priv(indio_dev);
> > +
> > + return sprintf(buf, "%u\n", data->near_level);
> > +}
> > +
> > +static const struct iio_chan_spec_ext_info vcnl4000_ext_info[] = {
> > + {
> > + .name = "near_level",
>
> Generally having properties with a underscore in them breaks generic parsing
> of the property name by userspace applications. This is because we use
> underscores to separate different components (type, modifier, etc.) of the
> attribute from each other.
>
> Do you think calling this "nearlevel" would work?

That works as well. I'll change that for v3.

For my education: Is the type, modifier policy written down somewhere
(similar to
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/leds/leds-class.rst#n44
)?

Cheers,
-- Guido

>
> I know there are existing bad examples of properties that use an underscore,
> but we should try to limit introducing new ones.
>
> > + .shared = IIO_SEPARATE,
> > + .read = vcnl4000_read_near_level,
> > + },
> > + { /* sentinel */ }
> > +};
> > +
> > static const struct iio_chan_spec vcnl4000_channels[] = {
> > {
> > .type = IIO_LIGHT,
> > @@ -350,6 +371,7 @@ static const struct iio_chan_spec vcnl4000_channels[] = {
> > }, {
> > .type = IIO_PROXIMITY,
> > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> > + .ext_info = vcnl4000_ext_info,
> > }
> > };
> > @@ -439,6 +461,10 @@ static int vcnl4000_probe(struct i2c_client *client,
> > dev_dbg(&client->dev, "%s Ambient light/proximity sensor, Rev: %02x\n",
> > data->chip_spec->prod, data->rev);
> > + if (device_property_read_u32(&client->dev, "near-level",
> > + &data->near_level) < 0)
> > + data->near_level = 0;
> > +
> > indio_dev->dev.parent = &client->dev;
> > indio_dev->info = &vcnl4000_info;
> > indio_dev->channels = vcnl4000_channels;
>
>