Re: [PATCH v2 5/8] of: Add of_graph_get_port_by_id function

Laurent Pinchart
2014-09-11T09:26:57Z

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@pengutronix.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