Re: [PATCH v4 5/5] iio: adc: ad7606: add gain calibration support

[Angelo Dureghello]

Hi Andy,

On 08.05.2025 22:00, Andy Shevchenko wrote:
> On Thu, May 08, 2025 at 12:06:09PM +0200, Angelo Dureghello wrote:
> > From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
> > 
> > Add gain calibration support, using resistor values set on devicetree,
> > values to be set accordingly with ADC external RFilter, as explained in
> > the ad7606c-16 datasheet, rev0, page 37.
> > 
> > Usage example in the fdt yaml documentation.
> 
> ...
> 
> > +static int ad7606_chan_calib_gain_setup(struct iio_dev *indio_dev)
> > +{
> > +	struct ad7606_state *st = iio_priv(indio_dev);
> > +	unsigned int num_channels = st->chip_info->num_adc_channels;
> > +	struct device *dev = st->dev;
> > +	int ret;
> > +
> > +	/*
> > +	 * This function is called once, and parses all the channel nodes,
> > +	 * so continuing on next channel node on errors, informing of them.
> > +	 */
> > +	device_for_each_child_node_scoped(dev, child) {
> > +		u32 reg, r_gain;
> > +
> > +		ret = fwnode_property_read_u32(child, "reg", &reg);
> > +		if (ret)
> > +			continue;
> 
> > +		/* Chan reg is a 1-based index. */
> > +		if (reg < 1 || reg > num_channels) {
> > +			dev_warn(dev, "wrong ch number (ignoring): %d\n", reg);
> > +			continue;
> > +		}
> 
> But this will allow to have a broken DT. This check basically diminishes the
> effort of the DT schema validation. If there are limits one still would be able
> to create a DT that passes the driver but doesn't pass the validation.
> 

fixed all your points on other patches of this patch-set. Still your
emails are going to google spam, just could catch them on friday. 
Really not clear why.

About the above, i understand, but the check is actually the same as
in ad7606_get_chan_config(), a warning that fdt is not correct, 
i dont see a blocking issue here now, so not going to change it
in this next patchset.

Regards,
angelo

> > +		ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
> > +					       &r_gain);
> > +		if (ret)
> > +			/* Keep the default register value. */
> > +			continue;
> > +
> > +		if (r_gain > AD7606_CALIB_GAIN_MAX) {
> > +			dev_warn(dev, "wrong gain calibration value");
> > +			continue;
> > +		}
> > +
> > +		ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(reg - 1),
> > +			DIV_ROUND_CLOSEST(r_gain, AD7606_CALIB_GAIN_STEP));
> > +		if (ret) {
> > +			dev_warn(dev, "error writing r_gain");
> > +			continue;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>