linux-kernel - Re: [PATCH v1 2/3] device property: Add fwnode_graph_get_port

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Date:   Thu, 18 May 2017 16:36:26 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Kieran Bingham <kbingham@...nel.org>
Cc:     linux-renesas-soc@...r.kernel.org, linux-media@...r.kernel.org,
        sakari.ailus@....fi, niklas.soderlund@...natech.se,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        John Youn <johnyoun@...opsys.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/3] device property: Add fwnode_graph_get_port_parent

Hi Kieran,

Thank you for the patch.

On Wednesday 17 May 2017 16:03:38 Kieran Bingham wrote:
> From: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> 
> V4L2 async notifiers can pass the endpoint fwnode rather than the device
> fwnode.

I'm not sure I would mention V4L2 in the commit message, as this is generic.

> Provide a helper to obtain the parent device fwnode without first
> parsing the remote-endpoint as per fwnode_graph_get_remote_port_parent.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> ---
>  drivers/base/property.c  | 25 +++++++++++++++++++++++++
>  include/linux/property.h |  2 ++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 627ebc9b570d..caf4316fe565 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -1245,6 +1245,31 @@ fwnode_graph_get_next_endpoint(struct fwnode_handle
> *fwnode, EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);
> 
>  /**
> + * fwnode_graph_get_port_parent - Return device node of a port endpoint
> + * @fwnode: Endpoint firmware node pointing of the port
> + *
> + * Extracts firmware node of the device the @fwnode belongs to.

I'm not too familiar with the fwnode API, but I know it's written in C, where 
functions don't extract something but return a value :-) How about

Return: the firmware node of the device the @endpoint belongs to.

> + */
> +struct fwnode_handle *
> +fwnode_graph_get_port_parent(struct fwnode_handle *fwnode)

This is akin to writing (unsigned int integer)

How about calling the variable endpoint ? That would also make the 
documentation clearer in my opinion, with "the @fwnode belongs to" replaced 
with "the @endpoint belongs to".

> +{
> +	struct fwnode_handle *parent = NULL;
> +
> +	if (is_of_node(fwnode)) {
> +		struct device_node *node;
> +
> +		node = of_graph_get_port_parent(to_of_node(fwnode));
> +		if (node)
> +			parent = &node->fwnode;

This part looks good to me, with the above small change,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> +	} else if (is_acpi_node(fwnode)) {
> +		parent = acpi_node_get_parent(fwnode);

I can't comment on this one though.

> +	}
> +
> +	return parent;
> +}
> +EXPORT_SYMBOL_GPL(fwnode_graph_get_port_parent);
> +
> +/**
>   * fwnode_graph_get_remote_port_parent - Return fwnode of a remote device
>   * @fwnode: Endpoint firmware node pointing to the remote endpoint
>   *
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 2f482616a2f2..624129b86c82 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -274,6 +274,8 @@ void *device_get_mac_address(struct device *dev, char
> *addr, int alen);
> 
>  struct fwnode_handle *fwnode_graph_get_next_endpoint(
>  	struct fwnode_handle *fwnode, struct fwnode_handle *prev);
> +struct fwnode_handle *fwnode_graph_get_port_parent(
> +	struct fwnode_handle *fwnode);
>  struct fwnode_handle *fwnode_graph_get_remote_port_parent(
>  	struct fwnode_handle *fwnode);
>  struct fwnode_handle *fwnode_graph_get_remote_port(

-- 
Regards,

Laurent Pinchart