Re: [PATCH v5 1/5] driver core: Introduce device_{add,remove}_of_node()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Dec 09, 2024 at 02:03:33PM +0100, Herve Codina wrote:
> An of_node can be set to a device using device_set_node().
> This function cannot prevent any of_node and/or fwnode overwrites.
> 
> When adding an of_node on an already present device, the following
> operations need to be done:
> - Attach the of_node if no of_node were already attached
> - Attach the of_node as a fwnode if no fwnode were already attached
> 
> This is the purpose of device_add_of_node().
> device_remove_of_node() reverts the operations done by
> device_add_of_node().
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> ---
>  drivers/base/core.c    | 54 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/device.h |  2 ++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 8b056306f04e..81e5465aa746 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -5216,6 +5216,60 @@ void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
>  }
>  EXPORT_SYMBOL_GPL(set_secondary_fwnode);
>  
> +/**
> + * device_remove_of_node - Remove an of_node from a device
> + * @dev: device whose device-tree node is being removed
> + */
> +void device_remove_of_node(struct device *dev)
> +{
> +	dev = get_device(dev);
> +	if (!dev)
> +		return;
> +
> +	if (!dev->of_node)
> +		goto end;
> +
> +	if (dev->fwnode == of_fwnode_handle(dev->of_node))
> +		dev->fwnode = NULL;
> +
> +	of_node_put(dev->of_node);
> +	dev->of_node = NULL;
> +
> +end:
> +	put_device(dev);
> +}
> +EXPORT_SYMBOL_GPL(device_remove_of_node);
> +
> +/**
> + * device_add_of_node - Add an of_node to an existing device
> + * @dev: device whose device-tree node is being added
> + * @of_node: of_node to add
> + */
> +void device_add_of_node(struct device *dev, struct device_node *of_node)

Why is this void?

> +{
> +	if (!of_node)
> +		return;
> +
> +	dev = get_device(dev);
> +	if (!dev)
> +		return;
> +
> +	if (dev->of_node) {
> +		dev_warn(dev, "Cannot replace node %pOF with %pOF\n",
> +			 dev->of_node, of_node);

Why not return an error too?  Otherwise you can never know if this
worked or not.

thanks,

greg k-h