Re: [PATCH 1/3] staging: iio: adc: ad7280a: split ad7280_channel_init() to more functions

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Mon, 3 Dec 2018 21:06:41 +0100
Slawomir Stepien <sst@poczta.fm> wrote:

> On gru 02, 2018 15:45, Jonathan Cameron wrote:
> > On Sun,  2 Dec 2018 12:58:28 +0100
> > Slawomir Stepien <sst@poczta.fm> wrote:
> >   
> > > The ad7280_channel_init function has been split into more specific
> > > functions to increase the code readability.
> > > 
> > > Signed-off-by: Slawomir Stepien <sst@poczta.fm>  
> > Hi Slawomir,  
> 
> Hi
> 
> > A few comments inline.  I agree with the basic idea, but suggest
> > a slight different balance in where things are handled.  
> 
> Thank you for the review. I agree with the comments, but please see one remark
> below.
> 
> > > ---
> > >  drivers/staging/iio/adc/ad7280a.c | 119 +++++++++++++++++++-----------
> > >  1 file changed, 77 insertions(+), 42 deletions(-)
> > > 
> > > diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> > > index 7a0ba26f9fd9..a6b1bdd9f372 100644
> > > --- a/drivers/staging/iio/adc/ad7280a.c
> > > +++ b/drivers/staging/iio/adc/ad7280a.c
> > > @@ -496,6 +496,75 @@ static const struct attribute_group ad7280_attrs_group = {
> > >  	.attrs = ad7280_attributes,
> > >  };
> > >  
> > > +static void ad7280_voltage_channel_init(struct ad7280_state *st, int cnt,
> > > +					int dev, int ch)
> > > +{
> > > +	struct iio_chan_spec *chan = &st->channels[cnt];  
> > 
> > Pass the chan spec in here instead of the _state structure.
> > It will give cleaner code and better visibility on the scope of
> > this function where it is called.
> >   
> > > +
> > > +	chan->type = IIO_VOLTAGE;
> > > +	chan->differential = 1;
> > > +	chan->channel = (dev * 6) + ch;  
> > 
> > This offset does seem more than a little random buried away in this function.
> > I would pass it in explicitly as a parameter so that the we have all the
> > channel number manipulations visible in one place.
> >   
> > > +	chan->channel2 = chan->channel + 1;
> > > +}
> > > +
> > > +static void ad7280_temp_channel_init(struct ad7280_state *st, int cnt, int dev,
> > > +				     int ch)
> > > +{
> > > +	struct iio_chan_spec *chan = &st->channels[cnt];
> > > +
> > > +	chan->type = IIO_TEMP;
> > > +	chan->channel = (dev * 6) + ch - 6;  
> > This one is even more obscure when found in here. Pass it in as an additional parameter.  
> > > +}
> > > +
> > > +static void ad7280_common_fields_init(struct ad7280_state *st, int cnt, int dev,
> > > +				      int ch)  
> > 
> > It's not really the common fields given the voltage version is different.
> > Perhaps there is a better name for this function?  
> 
> I don't understand. The fields of the chan in this function are set to the same
> values for volt and temp channels (this function is called at the end of the
> for loop regardless of the AD type of the channel). I do not see how the voltage
> version is different.

It's the all voltage one that is different.  My mistake.

> 
> > > +{
> > > +	struct iio_chan_spec *chan = &st->channels[cnt];
> > > +
> > > +	chan->indexed = 1;
> > > +	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> > > +	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> > > +	chan->address = ad7280a_devaddr(dev) << 8 | ch;
> > > +	chan->scan_index = cnt;
> > > +	chan->scan_type.sign = 'u';
> > > +	chan->scan_type.realbits = 12;
> > > +	chan->scan_type.storagebits = 32;
> > > +	chan->scan_type.shift = 0;  
> > 
> > I doubt there is any need to set shift and 0 is the obvious default
> > so no 'documentation' benefit in doing it here.
> >   
> > > +}
> > > +
> > > +static void ad7280_all_voltage_channel_init(struct ad7280_state *st, int cnt,
> > > +					    int dev)  
> > Total voltage perhaps rather than 'all'?   
> > > +{
> > > +	struct iio_chan_spec *chan = &st->channels[cnt];
> > > +
> > > +	chan->type = IIO_VOLTAGE;
> > > +	chan->differential = 1;
> > > +	chan->channel = 0;
> > > +	chan->channel2 = dev * 6;
> > > +	chan->address = AD7280A_ALL_CELLS;
> > > +	chan->indexed = 1;
> > > +	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> > > +	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> > > +	chan->scan_index = cnt;
> > > +	chan->scan_type.sign = 'u';
> > > +	chan->scan_type.realbits = 32;
> > > +	chan->scan_type.storagebits = 32;
> > > +	chan->scan_type.shift = 0;
> > > +}
> > > +
> > > +static void ad7280_timestamp_channel_init(struct ad7280_state *st, int cnt)
> > > +{
> > > +	struct iio_chan_spec *chan = &st->channels[cnt];
> > > +
> > > +	chan->type = IIO_TIMESTAMP;
> > > +	chan->channel = -1;
> > > +	chan->scan_index = cnt;
> > > +	chan->scan_type.sign = 's';
> > > +	chan->scan_type.realbits = 64;
> > > +	chan->scan_type.storagebits = 64;
> > > +	chan->scan_type.shift = 0;
> > > +}
> > > +
> > >  static int ad7280_channel_init(struct ad7280_state *st)
> > >  {
> > >  	int dev, ch, cnt;
> > > @@ -508,51 +577,17 @@ static int ad7280_channel_init(struct ad7280_state *st)
> > >  	for (dev = 0, cnt = 0; dev <= st->slave_num; dev++)
> > >  		for (ch = AD7280A_CELL_VOLTAGE_1; ch <= AD7280A_AUX_ADC_6;
> > >  			ch++, cnt++) {
> > > -			if (ch < AD7280A_AUX_ADC_1) {
> > > -				st->channels[cnt].type = IIO_VOLTAGE;
> > > -				st->channels[cnt].differential = 1;
> > > -				st->channels[cnt].channel = (dev * 6) + ch;
> > > -				st->channels[cnt].channel2 =
> > > -					st->channels[cnt].channel + 1;
> > > -			} else {
> > > -				st->channels[cnt].type = IIO_TEMP;
> > > -				st->channels[cnt].channel = (dev * 6) + ch - 6;
> > > -			}
> > > -			st->channels[cnt].indexed = 1;
> > > -			st->channels[cnt].info_mask_separate =
> > > -				BIT(IIO_CHAN_INFO_RAW);
> > > -			st->channels[cnt].info_mask_shared_by_type =
> > > -				BIT(IIO_CHAN_INFO_SCALE);
> > > -			st->channels[cnt].address =
> > > -				ad7280a_devaddr(dev) << 8 | ch;
> > > -			st->channels[cnt].scan_index = cnt;
> > > -			st->channels[cnt].scan_type.sign = 'u';
> > > -			st->channels[cnt].scan_type.realbits = 12;
> > > -			st->channels[cnt].scan_type.storagebits = 32;
> > > -			st->channels[cnt].scan_type.shift = 0;
> > > +			if (ch < AD7280A_AUX_ADC_1)
> > > +				ad7280_voltage_channel_init(st, cnt, dev, ch);
> > > +			else
> > > +				ad7280_temp_channel_init(st, cnt, dev, ch);
> > > +
> > > +			ad7280_common_fields_init(st, cnt, dev, ch);
> > >  		}
> > >  
> > > -	st->channels[cnt].type = IIO_VOLTAGE;
> > > -	st->channels[cnt].differential = 1;
> > > -	st->channels[cnt].channel = 0;
> > > -	st->channels[cnt].channel2 = dev * 6;
> > > -	st->channels[cnt].address = AD7280A_ALL_CELLS;
> > > -	st->channels[cnt].indexed = 1;
> > > -	st->channels[cnt].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> > > -	st->channels[cnt].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
> > > -	st->channels[cnt].scan_index = cnt;
> > > -	st->channels[cnt].scan_type.sign = 'u';
> > > -	st->channels[cnt].scan_type.realbits = 32;
> > > -	st->channels[cnt].scan_type.storagebits = 32;
> > > -	st->channels[cnt].scan_type.shift = 0;
> > > +	ad7280_all_voltage_channel_init(st, cnt, dev);
> > >  	cnt++;
> > > -	st->channels[cnt].type = IIO_TIMESTAMP;
> > > -	st->channels[cnt].channel = -1;
> > > -	st->channels[cnt].scan_index = cnt;
> > > -	st->channels[cnt].scan_type.sign = 's';
> > > -	st->channels[cnt].scan_type.realbits = 64;
> > > -	st->channels[cnt].scan_type.storagebits = 64;
> > > -	st->channels[cnt].scan_type.shift = 0;
> > > +	ad7280_timestamp_channel_init(st, cnt);
> > >  
> > >  	return cnt + 1;
> > >  }  
> >   
>