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

[David Lechner <dlechner@baylibre.com>]

On 4/29/25 8:06 AM, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@baylibre.com>
> 

...

> +static int ad7606_chan_calib_gain_setup(struct iio_dev *indio_dev,
> +					struct iio_chan_spec *chan)
> +{
> +	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;
> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		int reg, r_gain;
> +
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
> +		if (ret)
> +			return ret;
> +
> +		/* channel number (here) is from 1 to num_channels */
> +		if (reg < 1 || reg > num_channels) {
> +			dev_warn(dev, "invalid ch number (ignoring): %d\n", reg);
> +			continue;
> +		}
> +
> +		ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
> +					       &r_gain);

Instead of...

> +		if (ret)
> +			return ret;

... we need:

		if (ret == -EINVAL)
			r_gain = 0;
		else if (ret)
			return ret;

Otherwise driver fails to probe if adi,rfilter-ohms is missing.

> +
> +		if (r_gain < AD7606_CALIB_GAIN_MIN ||
> +		    r_gain > AD7606_CALIB_GAIN_MAX)
> +			return -EINVAL;
> +

Also, return dev_err_probe() on the returns above would have made debugging
easier.

> +		/* Chan reg is 1-based index. */
> +		ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(reg - 1),
> +					  r_gain / AD7606_CALIB_GAIN_STEP);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +