linux-kernel - Re: [PATCH v7 6/6] iio: adc: ad7192: Add AD7194 support

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Date: Mon, 6 May 2024 14:39:28 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Alisa-Dariana Roman <alisadariana@...il.com>
Cc: michael.hennerich@...log.com, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 alexandru.tachici@...log.com, lars@...afoo.de, robh@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 lgirdwood@...il.com, broonie@...nel.org, andy@...nel.org,
 nuno.sa@...log.com, marcelo.schmitt@...log.com, bigunclemax@...il.com,
 dlechner@...libre.com, okan.sahin@...log.com, fr0st61te@...il.com,
 alisa.roman@...log.com, marcus.folkesson@...il.com, schnelle@...ux.ibm.com,
 liambeguin@...il.com
Subject: Re: [PATCH v7 6/6] iio: adc: ad7192: Add AD7194 support

On Tue, 30 Apr 2024 19:29:46 +0300
Alisa-Dariana Roman <alisadariana@...il.com> wrote:

> Unlike the other AD719Xs, AD7194 has configurable channels. The user can
> dynamically configure them in the devicetree.
> 
> Also modify config AD7192 description for better scaling.
> 
> Signed-off-by: Alisa-Dariana Roman <alisa.roman@...log.com>

Hi Alisa-Dariana,

I only had one minor thing to add to the other reviews,

Thanks,

Jonathan

>  	  To compile this driver as a module, choose M here: the
> diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> index 3e797ff48086..0f6ecf953559 100644
> --- a/drivers/iio/adc/ad7192.c
> +++ b/drivers/iio/adc/ad7192.c
..

> +static int ad7194_parse_channels(struct iio_dev *indio_dev)
> +{
> +	struct device *dev = indio_dev->dev.parent;
> +	struct iio_chan_spec *ad7194_channels;
> +	struct fwnode_handle *child;
> +	struct iio_chan_spec ad7194_chan = AD7193_CHANNEL(0, 0, 0);

I think you are only using these as templates that get copied?
If so declare them const.

> +	struct iio_chan_spec ad7194_chan_diff = AD7193_DIFF_CHANNEL(0, 0, 0, 0);
> +	struct iio_chan_spec ad7194_chan_temp = AD719x_TEMP_CHANNEL(0, 0);
> +	struct iio_chan_spec ad7194_chan_timestamp = IIO_CHAN_SOFT_TIMESTAMP(0);
> +	unsigned int num_channels, index = 0;
> +	u32 ain[2];
> +	int ret;
> +
> +	num_channels = device_get_child_node_count(dev);
> +	if (num_channels > AD7194_CH_MAX_NR)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Too many channels: %u\n", num_channels);
> +
> +	num_channels += AD7194_CH_BASE_NR;
> +
> +	ad7194_channels = devm_kcalloc(dev, num_channels,
> +				       sizeof(*ad7194_channels), GFP_KERNEL);
> +	if (!ad7194_channels)
> +		return -ENOMEM;
> +
> +	indio_dev->channels = ad7194_channels;
> +	indio_dev->num_channels = num_channels;
> +
> +	device_for_each_child_node(dev, child) {

Andy pointed out the need for scoped here to avoid leaking the fwnode in error paths.

> +		ret = fwnode_property_read_u32_array(child, "diff-channels",
> +						     ain, ARRAY_SIZE(ain));
> +		if (ret == 0) {
> +			ret = ad7194_validate_ain_channel(dev, ain[0]);
> +			if (ret)
> +				return ret;
> +
> +			ret = ad7194_validate_ain_channel(dev, ain[1]);
> +			if (ret)
> +				return ret;
> +
> +			*ad7194_channels = ad7194_chan_diff;
> +			ad7194_channels->scan_index = index++;
> +			ad7194_channels->channel = ain[0];
> +			ad7194_channels->channel2 = ain[1];
> +			ad7194_channels->address = AD7194_CH(ain[0], ain[1]);
> +		} else {
> +			ret = fwnode_property_read_u32(child, "single-channel",
> +						       &ain[0]);
> +			if (ret) {
> +				fwnode_handle_put(child);

With scoped variant above you can drop this one case of (currently correct)
release of the fwnode.

> +				return ret;
> +			}
> +
> +			ret = ad7194_validate_ain_channel(dev, ain[0]);
> +			if (ret)
> +				return ret;
> +
> +			*ad7194_channels = ad7194_chan;
> +			ad7194_channels->scan_index = index++;
> +			ad7194_channels->channel = ain[0];
> +			ad7194_channels->address = AD7194_CH(ain[0], 0);
> +		}
> +		ad7194_channels++;
> +	}
> +
> +	*ad7194_channels = ad7194_chan_temp;
> +	ad7194_channels->scan_index = index++;
> +	ad7194_channels->address = AD7194_CH_TEMP;
> +	ad7194_channels++;
> +
> +	*ad7194_channels = ad7194_chan_timestamp;
> +	ad7194_channels->scan_index = index;
> +
> +	return 0;
> +}