Re: [PATCH v4 4/9] iio: dac: mcp47feb02: use dev_dbg for invalid label

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Making the label property optional causes the `label` sysfs attribute to return the literal string `(null)` for channels without a label.
--

--- Patch [4]: [PATCH v4 4/9] iio: dac: mcp47feb02: use dev_dbg for invalid label ---
commit 60f7652ad06abf540ec40667fe14b057bf9a477b
Author: Ariana Lazar <ariana.lazar@microchip.com>

iio: dac: mcp47feb02: use dev_dbg for invalid label

This commit modifies the firmware parsing logic to tolerate missing or
invalid label properties. Instead of aborting the probe with an error, it
logs a debug message and continues initialization.

> diff --git a/drivers/iio/dac/mcp47feb02.c b/drivers/iio/dac/mcp47feb02.c
> index 2ee981393aa1a..e5533fa3c31c0 100644
> --- a/drivers/iio/dac/mcp47feb02.c
> +++ b/drivers/iio/dac/mcp47feb02.c

[ ... ]

> @@ -978,8 +979,7 @@ static int mcp47feb02_parse_fw(struct iio_dev *indio_dev,
>  
>  		ret = fwnode_property_read_string(child, "label", &data->labels[reg]);
>  		if (ret)
> -			return dev_err_probe(dev, ret, "%pfw: invalid label\n",
> -					     fwnode_get_name(child));
> +			dev_dbg(dev, "%s: invalid label\n", fwnode_get_name(child));

[Severity: Medium]
When the label property is invalid or missing, data->labels[reg] will
now remain NULL.

Because the IIO core still registers the label sysfs attribute when
the read_label callback is populated, could this introduce a regression
where mcp47feb02_read_label() outputs the literal string "(null)"?

drivers/iio/dac/mcp47feb02.c:mcp47feb02_read_label() {
	struct mcp47feb02_data *data = iio_priv(indio_dev);

	return sysfs_emit(label, "%s\n", data->labels[ch->address]);
}

Since sysfs_emit() unconditionally formats a NULL pointer as "(null)",
userspace tools might parse "(null)" as the channel's actual label. Should
mcp47feb02_read_label() handle the NULL case and return an error code like
-ENOENT instead?

>  
>  		chanspec.address = reg;
>  		chanspec.channel = reg;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260819-mcp47feb02_refactor-v4-0-beb2aa3bfd09@microchip.com?part=4