linux-kernel - Re: [PATCH v8 2/2] iio: adc: ad7173: add AD7173 driver

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Date:   Thu, 14 Dec 2023 12:30:29 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Dumitru Ceclan <mitrutzceclan@...il.com>
CC:     <linus.walleij@...aro.org>, <brgl@...ev.pl>, <andy@...nel.org>,
        <linux-gpio@...r.kernel.org>, Lars-Peter Clausen <lars@...afoo.de>,
        "Jonathan Cameron" <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Michael Walle <michael@...le.cc>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        Leonard Göhrs <l.goehrs@...gutronix.de>,
        Mike Looijmans <mike.looijmans@...ic.nl>,
        Haibo Chen <haibo.chen@....com>,
        Hugo Villeneuve <hvilleneuve@...onoff.com>,
        Ceclan Dumitru <dumitru.ceclan@...log.com>,
        <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 2/2] iio: adc: ad7173: add AD7173 driver

On Tue, 12 Dec 2023 12:44:36 +0200
Dumitru Ceclan <mitrutzceclan@...il.com> wrote:

> The AD7173 family offer a complete integrated Sigma-Delta ADC solution
> which can be used in high precision, low noise single channel
> applications or higher speed multiplexed applications. The Sigma-Delta
> ADC is intended primarily for measurement of signals close to DC but also
> delivers outstanding performance with input bandwidths out to ~10kHz.
> 
> Reviewed-by: Michael Walle <michael@...le.cc> # for gpio-regmap
> Signed-off-by: Dumitru Ceclan <mitrutzceclan@...il.com>
Hi

Given it seems like you'll be doing a v9, one quick comment from me below.

Jonathan

> diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
> new file mode 100644
> index 000000000000..96918b24a10a
> --- /dev/null
> +++ b/drivers/iio/adc/ad7173.c
> @@ -0,0 +1,964 @@
...

> +static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
> +{

...

> +
> +	if (st->info->has_temp) {
> +		chan_arr[chan_index] = ad7173_temp_iio_channel_template;
> +		chan_st_priv = &channels_st_priv_arr[chan_index];
> +		chan_st_priv->ain =
> +			AD7173_CH_ADDRESS(chan_arr[chan_index].channel, chan_arr[chan_index].channel2);
> +		chan_st_priv->cfg.bipolar = false;
> +		chan_st_priv->cfg.input_buf = true;
> +		chan_st_priv->cfg.ref_sel = AD7173_SETUP_REF_SEL_INT_REF;
> +		st->adc_mode |= AD7173_ADC_MODE_REF_EN;
> +
> +		chan_index++;
> +	}
> +
> +	device_for_each_child_node(dev, child) {
> +		chan = &chan_arr[chan_index];
> +		chan_st_priv = &channels_st_priv_arr[chan_index];
> +		ret = fwnode_property_read_u32_array(child, "diff-channels",
> +						     ain, ARRAY_SIZE(ain));
> +		if (ret) {
> +			fwnode_handle_put(child);
> +			return ret;
> +		}
> +
> +		if (ain[0] >= st->info->num_inputs ||
> +		    ain[1] >= st->info->num_inputs) {
> +			fwnode_handle_put(child);
> +			return dev_err_probe(dev, -EINVAL,
> +					     "Input pin number out of range for pair (%d %d).\n",
> +					     ain[0], ain[1]);
> +		}
> +
> +		ret = fwnode_property_match_property_string(child,
> +							    "adi,reference-select",
> +							    ad7173_ref_sel_str,
> +							    ARRAY_SIZE(ad7173_ref_sel_str));
> +
> +		if (ret < 0)
> +			ref_sel = AD7173_SETUP_REF_SEL_INT_REF;
> +		else
> +			ref_sel = ret;
Simpler pattern for properties with a default is not to check the error code.

		ref_sel = AD7173_SETUP_REF_SEL_INT_REF;

		fwnode_property_match_property_String(child, ...

so only if it succeeds is the value overridden.