linux-kernel - Re: [PATCH v2 5/8] of: Add of_graph_get_port_by

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Date:	Thu, 11 Sep 2014 12:26:58 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	devel@...verdev.osuosl.org, Grant Likely <grant.likely@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	kernel@...gutronix.de
Subject: Re: [PATCH v2 5/8] of: Add of_graph_get_port_by_id function

Hi Philipp,

Thank you for the patch.

On Wednesday 10 September 2014 12:58:25 Philipp Zabel wrote:
> This patch adds a function to get a port device tree node by port id,
> or reg property value.
> 
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
> Changes since v1:
>  - Fixed whitespace in comment
>  - Changed id parameter to of_graph_get_port_by_id to u32
>  - Simplified of_graph_get_port_by_id as suggested by Laurent,
>    making use of port id defaulting to 0 if no "reg" property is given.
> ---
>  drivers/of/base.c        | 26 ++++++++++++++++++++++++++
>  include/linux/of_graph.h |  7 +++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index a49b5628..b282474 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2053,6 +2053,32 @@ int of_graph_parse_endpoint(const struct device_node
> *node, EXPORT_SYMBOL(of_graph_parse_endpoint);
> 
>  /**
> + * of_graph_get_port_by_id() - get the port matching a given id
> + * @parent: pointer to the parent device node
> + * @id: id of the port
> + *
> + * Return: A 'port' node pointer with refcount incremented. The caller
> + * has to use of_node_put() on it when done.
> + */
> +struct device_node *of_graph_get_port_by_id(struct device_node *node, u32
> id) +{
> +	struct device_node *port = NULL;

No need to initialize port to NULL.

> +	u32 port_id = 0;
> +
> +	while (true) {
> +		port = of_get_next_child(node, port);
> +		if (!port)
> +			return NULL;

How about using for_each_child_of_node() ?

> +		if (of_node_cmp(port->name, "port") != 0)
> +			continue;
> +		of_property_read_u32(port, "reg", &port_id);

A port with no reg property will be treated as having the id of the previous 
port. You can fix this by moving the port_id variable declaration inside the 
loop.

> +		if (id == port_id)
> +			return port;
> +	}
> +}
> +EXPORT_SYMBOL(of_graph_get_port_by_id);
> +
> +/**
>   * of_graph_get_next_endpoint() - get next endpoint node
>   * @parent: pointer to the parent device node
>   * @prev: previous endpoint node, or NULL to get first
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index e43442e..e028e49 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -40,6 +40,7 @@ struct of_endpoint {
>  #ifdef CONFIG_OF
>  int of_graph_parse_endpoint(const struct device_node *node,
>  				struct of_endpoint *endpoint);
> +struct device_node *of_graph_get_port_by_id(struct device_node *node, u32
> id); struct device_node *of_graph_get_next_endpoint(const struct
> device_node *parent, struct device_node *previous);
>  struct device_node *of_graph_get_remote_port_parent(
> @@ -53,6 +54,12 @@ static inline int of_graph_parse_endpoint(const struct
> device_node *node, return -ENOSYS;
>  }
> 
> +static inline struct device_node *of_graph_get_port_by_id(
> +					struct device_node *node, int id)

id should be u32 here.

> +{
> +	return NULL;
> +}
> +
>  static inline struct device_node *of_graph_get_next_endpoint(
>  					const struct device_node *parent,
>  					struct device_node *previous)

-- 
Regards,

Laurent Pinchart

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