Re: [PATCH v4 3/5] iio: backend: add devm_iio_backend_get_by_index()

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Feb 23, 2026 at 06:21:02PM +0200, Antoniu Miclaus wrote:
> Add a new function to get an IIO backend by its index in the
> io-backends device tree property. This is useful for multi-channel
> devices that have multiple backends, where looking up by index is
> more straightforward than using named backends.
> 
> The new function directly uses the index to find the backend reference
> in the io-backends property, avoiding the need for io-backend-names.

...

> +static struct iio_backend *
> +__devm_iio_backend_fwnode_get_by_index(struct device *dev,
> +				       struct fwnode_handle *fwnode,
> +				       unsigned int index)
>  {

> +	struct fwnode_handle *fwnode_back __free(fwnode_handle) =
> +		fwnode_find_reference(fwnode, "io-backends", index);

Better for maintenance to have this near to the check.
It will narrow down the scope as required, in case more code appear in between.

>  	struct iio_backend *back;
>  	int ret;
>  

(yes, the above blank line is fine)

	struct fwnode_handle *fwnode_back __free(fwnode_handle) =
		fwnode_find_reference(fwnode, "io-backends", index);

>  	if (IS_ERR(fwnode_back))
>  		return dev_err_cast_probe(dev, fwnode_back,
>  					  "Cannot get Firmware reference\n");

>  		if (!device_match_fwnode(back->dev, fwnode_back))
>  			continue;
>  
> -		fwnode_handle_put(fwnode_back);
>  		ret = __devm_iio_backend_get(dev, back);
>  		if (ret)
>  			return ERR_PTR(ret);
>  
> -		if (name)
> -			back->idx = index;
> +		back->idx = index;
>  
>  		return back;
>  	}
>  
> -	fwnode_handle_put(fwnode_back);
>  	return ERR_PTR(-EPROBE_DEFER);
>  }

...

> +static struct iio_backend *__devm_iio_backend_fwnode_get(struct device *dev, const char *name,
> +							 struct fwnode_handle *fwnode)
> +{
> +	unsigned int index = 0;

Better to maintain when assignment is closer to the real use. See below.

> +	int ret;
> +
> +	if (name) {
> +		ret = device_property_match_string(dev, "io-backend-names",
> +						   name);

This can be located on a single line (it's only 82 characters long).

> +		if (ret < 0)
> +			return ERR_PTR(ret);
> +		index = ret;

	} else {
		index = 0;

> +	}
> +
> +	return __devm_iio_backend_fwnode_get_by_index(dev, fwnode, index);
> +}

-- 
With Best Regards,
Andy Shevchenko