Re: [PATCH v4 7/9] iio: dac: mcp47feb02: refactor MCP47FEB02 I2C driver into two modules

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Making the device tree 'label' property optional causes the literal string '(null)' to be printed to sysfs.
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--- Patch [7]: [PATCH v4 7/9] iio: dac: mcp47feb02: refactor MCP47FEB02 I2C driver into two modules ---
commit ed5f5f581011130b05d16462d5287ab79c40d657
Author: Ariana Lazar <ariana.lazar@microchip.com>

iio: dac: mcp47feb02: refactor MCP47FEB02 I2C driver into two modules

This commit refactors the MCP47FEB02 driver into a core module and an
I2C-specific module to prepare for future SPI support.

> diff --git a/drivers/iio/dac/mcp47feb02.c b/drivers/iio/dac/mcp47feb02-core.c
> rename from drivers/iio/dac/mcp47feb02.c
> rename to drivers/iio/dac/mcp47feb02-core.c
> index a823c2a673a26..8bee01a823673 100644
> --- a/drivers/iio/dac/mcp47feb02.c
> +++ b/drivers/iio/dac/mcp47feb02-core.c
[ ... ]
> @@ -978,8 +773,7 @@ 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));
>  
>  		chanspec.address = reg;
>  		chanspec.channel = reg;

[Severity: Medium]
Will this cause an unintended sysfs output when a channel lacks the label
property?

By continuing the probe without an error, data->labels[reg] remains NULL.
When userspace later reads the label via sysfs, mcp47feb02_read_label()
passes this pointer to sysfs_emit():

mcp47feb02_read_label() {
	...
	return sysfs_emit(label, "%s\n", data->labels[ch->address]);
}

Passing a NULL pointer to sysfs_emit() will print the literal string
"(null)\n" to userspace instead of returning a standard error like -ENOENT.

Would it be better to add a NULL check in mcp47feb02_read_label() before
emitting the string?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260819-mcp47feb02_refactor-v4-0-beb2aa3bfd09@microchip.com?part=7