Re: [PATCH v4 2/2] iio: adc: ad7173: add openwire detection support for single conversions

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 20 Jan 2025 17:07:24 +0000
Nuno Sá <noname.nuno@gmail.com> wrote:

> On Mon, 2025-01-20 at 15:10 +0100, Guillaume Ranquet wrote:
> > Some chips of the ad7173 family supports open wire detection.
> > 
> > Generate a level fault event whenever an external source is disconnected
> > from the system input on single conversions.
> > 
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > ---  
> 
> LGTM... Just one small nit. In any case:
> 
> Reviewed-by: Nuno Sa <nuno.sa@analog.com>
> 
> >  drivers/iio/adc/ad7173.c | 166
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 166 insertions(+)
> > 
> > diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
> > index
> > 11ff148cb5a315d32485acf04b8d6f7d0fb6e5fa..a2ea8f7ae8e61f1f3cdfba795551de2db96b
> > 8d60 100644
> > --- a/drivers/iio/adc/ad7173.c
> > +++ b/drivers/iio/adc/ad7173.c
> > @@ -35,6 +35,7 @@
> >  #include <linux/units.h>
> >  
> >  #include <linux/iio/buffer.h>
> > +#include <linux/iio/events.h>
> >  #include <linux/iio/iio.h>
> >  #include <linux/iio/trigger_consumer.h>
> >  #include <linux/iio/triggered_buffer.h>
> > @@ -102,6 +103,7 @@
> >  
> >  #define AD7173_GPIO_PDSW	BIT(14)
> >  #define AD7173_GPIO_OP_EN2_3	BIT(13)
> > +#define AD4111_GPIO_GP_OW_EN	BIT(12)
> >  #define AD7173_GPIO_MUX_IO	BIT(12)
> >  #define AD7173_GPIO_SYNC_EN	BIT(11)
> >  #define AD7173_GPIO_ERR_EN	BIT(10)
> > @@ -149,6 +151,7 @@
> >   
> 
> ...
> 
> > 
> > +
> >  static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
> >  {
> >  	struct ad7173_channel *chans_st_arr, *chan_st_priv;
> > @@ -1375,6 +1528,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev
> > *indio_dev)
> >  		chan_st_priv->cfg.bipolar = false;
> >  		chan_st_priv->cfg.input_buf = st->info->has_input_buf;
> >  		chan_st_priv->cfg.ref_sel = AD7173_SETUP_REF_SEL_INT_REF;
> > +		chan_st_priv->cfg.openwire_comp_chan = -1;
> >  		st->adc_mode |= AD7173_ADC_MODE_REF_EN;
> >  		if (st->info->data_reg_only_16bit)
> >  			chan_arr[chan_index].scan_type = ad4113_scan_type;
> > @@ -1442,6 +1596,7 @@ static int ad7173_fw_parse_channel_config(struct iio_dev
> > *indio_dev)
> >  		chan_st_priv->chan_reg = chan_index;
> >  		chan_st_priv->cfg.input_buf = st->info->has_input_buf;
> >  		chan_st_priv->cfg.odr = 0;
> > +		chan_st_priv->cfg.openwire_comp_chan = -1;
> >  
> >  		chan_st_priv->cfg.bipolar = fwnode_property_read_bool(child,
> > "bipolar");
> >  		if (chan_st_priv->cfg.bipolar)
> > @@ -1456,6 +1611,17 @@ static int ad7173_fw_parse_channel_config(struct
> > iio_dev *indio_dev)
> >  			chan_st_priv->cfg.input_buf = st->info-  
> > >has_input_buf;  
> >  			chan->channel2 = ain[1];
> >  			chan_st_priv->ain = AD7173_CH_ADDRESS(ain[0],
> > ain[1]);
> > +			if (st->info->has_openwire_det &&
> > +			    ad7173_validate_openwire_ain_inputs(st, chan-  
> > >differential, ain[0], ain[1])) {  
> > +				chan->event_spec = ad4111_events;
> > +				chan->num_event_specs =
> > ARRAY_SIZE(ad4111_events);
> > +				chan_st_priv->cfg.openwire_thrsh_raw =
> > +					BIT(chan->scan_type.realbits -
> > !!(chan_st_priv->cfg.bipolar))
> > +					* AD4111_OW_DET_THRSH_MV
> > +					/ ad7173_get_ref_voltage_milli(st,
> > chan_st_priv->cfg.ref_sel);
> > +				if (chan->channel < st->info-  
> > >num_voltage_in_div)  
> > +					chan_st_priv->cfg.openwire_thrsh_raw
> > /= AD4111_DIVIDER_RATIO;
> > +			}  
> 
> If you need to send another version for some reason, might be worth it to
> implement a simple helper for the above to improve code readability.
> 
> Maybe is just me but that 'chan_st_priv->cfg.openwire_thrsh_raw =' is fairly
> unreadable :)
> 
This crossed with a set from David and doesn't apply. Please rebase on top
of my testing branch.  Thanks! If the helper function Nuno suggests makes
sense to you feel free to do that as well.

The two patches I have on this driver that aren't upstream yet are:
iio: adc: ad7173: don't make copy of ad_sigma_delta_info struct 
iio: adc: ad7173: move fwnode_irq_get_byname() call site

Jonathan
> - Nuno Sá
> >