On Fri, 17 Jan 2025 10:59:04 +0100
Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx> wrote:
> Hello,
>
> On Fri, Dec 20, 2024 at 02:01:34PM +0200, Antoniu Miclaus wrote:
> > +static const int ad4851_oversampling_ratios[] = {
> > + 1, 2, 4, 8, 16, 32, 64, 128,
> > + 256, 512, 1024, 2048, 4096, 8192, 16384, 32768,
> > + 65536,
> > +};
> > +
> > +static int ad4851_osr_to_regval(unsigned int ratio)
> > +{
> > + int i;
> > +
> > + for (i = 1; i < ARRAY_SIZE(ad4851_oversampling_ratios); i++)
> > + if (ratio == ad4851_oversampling_ratios[i])
> > + return i - 1;
> > +
> > + return -EINVAL;
> > +}
>
> This can be simplified (I guess) using something like:
>
> if (ratio >= 2 && ratio <= 65536 && is_power_of_2(ratio))
> return ilog2(ratio) - 1;
>
> return -EINVAL;
Hi Uwe,
Only at the cost of providing custom handling to compute the above
array in order to provide it to userspace via the read_avail() callback.
We could do what you have here and provide the array but that would
be less clear than just looking it up.
>
> > +static void __ad4851_get_scale(struct iio_dev *indio_dev, int scale_tbl,
> > + unsigned int *val, unsigned int *val2)
> > +{
> > [...]
> > +}
> > +
> > +static int ad4851_scale_fill(struct iio_dev *indio_dev)
> > +{
> > [...]
> > +}
> > +
> > +static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
> > + const struct iio_chan_spec *chan,
> > + unsigned int osr)
> > +{
> > [...]
> > +}
> > +
> > +static int ad4851_get_oversampling_ratio(struct ad4851_state *st, unsigned int *val)
> > +{
> > + unsigned int osr;
> > + int ret;
> > +
> > + guard(mutex)(&st->lock);
> > +
> > + ret = regmap_read(st->regmap, AD4851_REG_OVERSAMPLE, &osr);
> > + if (ret)
> > + return ret;
> > +
> > + if (!FIELD_GET(AD4851_OS_EN_MSK, osr))
> > + *val = 1;
> > + else
> > + *val = ad4851_oversampling_ratios[FIELD_GET(AD4851_OS_RATIO_MSK, osr) + 1];
>
> With the suggestion above this gets:
>
> *val = 2 << FIELD_GET(AD4851_OS_RATIO_MSK, osr);
>
> (or
> *val = 1 << (FIELD_GET(AD4851_OS_RATIO_MSK, osr) + 1);
>
> ). Then you can drop ad4851_oversampling_ratios[].
You missed the usage in as4851_read_avail() which is the reason it exists.
These others are just convenient given that it already exists.
Jonathan
>
> > +
> > + st->osr = *val;
> > +
> > + return IIO_VAL_INT;
> > +}
>
> Best regards
> Uwe
>
