Re: [PATCH v3 2/6] iio: adc: ad4030: add driver for ad4030-24

[Esteban Blanc]

On Fri Jan 31, 2025 at 7:14 PM CET, Jonathan Cameron wrote:
> On Thu, 30 Jan 2025 12:08:26 +0100
> Esteban Blanc <eblanc@xxxxxxxxxxxx> wrote:
>
> > This adds a new driver for the Analog Devices INC. AD4030-24 ADC.
> > 
> > The driver implements basic support for the AD4030-24 1 channel
> > differential ADC with hardware gain and offset control.
> > 
> > Signed-off-by: Esteban Blanc <eblanc@xxxxxxxxxxxx>
> Hi Esteban,
>
> Just one thing in here that actually matters. Question about scaling of
> the common channel.  The others I could tidy up whilst applying if
> nothing much else comes up.
>
> Jonathan
>
>
> > +static int ad4030_get_chan_scale(struct iio_dev *indio_dev,
> > +				 struct iio_chan_spec const *chan,
> > +				 int *val,
> > +				 int *val2)
> > +{
> > +	struct ad4030_state *st = iio_priv(indio_dev);
> > +
> > +	if (chan->differential) {
> > +		*val = (st->vref_uv * 2) / MILLI;
> > +		*val2 = st->chip->precision_bits;
> > +		return IIO_VAL_FRACTIONAL_LOG2;
> > +	}
> > +
> > +	*val = st->vref_uv / 256;
>
> This is a bit non obvious.
> A comment on this scaling might be good to have.
> Particularly the lack of / MILLI
> (I think that's a bug?)

Yes I think that should be:
``
*val = st->vref_uv / MILLI;
*val2 = 8;
return IIO_VAL_FRACTIONAL_LOG2;
``

So I guess that requires a V4. I will address the other comments there.

Thanks for your time,

-- 
Esteban "Skallwar" Blanc
BayLibre