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SubjectRe: [PATCH v7 2/3] iio: (bma400) add driver for the BMA400
On Thu, Dec 19, 2019 at 01:02:28PM +0200, Andy Shevchenko wrote:
> On Thu, Dec 19, 2019 at 6:27 AM Dan Robertson <dan@dlrobertson.com> wrote:
> > Add a IIO driver for the Bosch BMA400 3-axes ultra-low power accelerometer.
> > The driver supports reading from the acceleration and temperature
> > registers. The driver also supports reading and configuring the output data
> > rate, oversampling ratio, and scale.
>
> ...
>
> > +static int bma400_set_accel_output_data_rate(struct bma400_data *data,
> > + int hz, int uhz)
> > +{
> > + unsigned int idx;
> > + unsigned int odr;
> > + unsigned int val;
> > + int ret;
> > +
> > + if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
> > + if (uhz || hz % BMA400_ACC_ODR_MIN_WHOLE_HZ)
> > + return -EINVAL;
> > +
> > + val = hz / BMA400_ACC_ODR_MIN_WHOLE_HZ;
>
> Again, AFAICS division may be avoided in both cases (% and / above)
> because of is_power_of_2() check below.
> Can you revisit this?

Yeah I can update this in the next patchset, but I don't know if it is much more
readable this way.

> > + if (!is_power_of_2(val))
> > + return -EINVAL;
> > +
> > + idx = __ffs(val) + BMA400_ACC_ODR_MIN_RAW + 1;
> > + } else if (hz == BMA400_ACC_ODR_MIN_HZ && uhz == 500000) {
> > + idx = BMA400_ACC_ODR_MIN_RAW;
> > + } else {
> > + return -EINVAL;
> > + }
> > +
> > + ret = regmap_read(data->regmap, BMA400_ACC_CONFIG1_REG, &val);
> > + if (ret)
> > + return ret;
> > +
> > + /* preserve the range and normal mode osr */
>
> > + odr = idx | (~BMA400_ACC_ODR_MASK & val);
>
> Yoda style?

Fixed in v8.

> > +
> > + ret = regmap_write(data->regmap, BMA400_ACC_CONFIG1_REG, odr);
> > + if (ret)
> > + return ret;
> > +
> > + bma400_output_data_rate_from_raw(idx, &data->sample_freq.hz,
> > + &data->sample_freq.uhz);
> > + return 0;
> > +}
> ...
>
> > +int bma400_accel_scale_to_raw(struct bma400_data *data, unsigned int val)
> > +{
> > + int scale = val / BMA400_SCALE_MIN;
> > + int raw;
> > +
> > + if (scale == 0)
> > + return -EINVAL;
> > +
> > + raw = __ffs(scale);
> > +
> > + if (val % BMA400_SCALE_MIN || !is_power_of_2(scale))
> > + return -EINVAL;
>
> Ditto.
>
> > +
> > + return raw;
> > +}
>
> ...
>
> > +out:
>
> Make a little sense. Why not return directly?

Mostly setup for the next patch in this patchset.

> > + return ret;
>
> ...
>
> > + ret = bma400_init(data);
> > + if (ret < 0)
>
> May it be positive value returned?

Fixed in v8.

Cheers,

- Dan

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