[v5,1/6] of_graph: add of_graph_get_local_port()

In some case, like a DRM display code for example, it's useful to silently
check whether port node exists at all in a device-tree before proceeding
with parsing the graph.

This patch adds of_graph_get_local_port() which returns pointer to a local
port node, or NULL if graph isn't specified in a device-tree for a given
device node.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/of/property.c    | 32 +++++++++++++++++++++++---------
 include/linux/of_graph.h |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

On Sat, 18 Apr 2020 20:06:58 +0300, Dmitry Osipenko wrote:
> In some case, like a DRM display code for example, it's useful to silently
> check whether port node exists at all in a device-tree before proceeding
> with parsing the graph.
> 
> This patch adds of_graph_get_local_port() which returns pointer to a local
> port node, or NULL if graph isn't specified in a device-tree for a given
> device node.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/of/property.c    | 32 +++++++++++++++++++++++---------
>  include/linux/of_graph.h |  7 +++++++
>  2 files changed, 30 insertions(+), 9 deletions(-)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Hi Dmitry

On Sat, Apr 18, 2020 at 08:06:58PM +0300, Dmitry Osipenko wrote:
> In some case, like a DRM display code for example, it's useful to silently
> check whether port node exists at all in a device-tree before proceeding
> with parsing the graph.
> 
> This patch adds of_graph_get_local_port() which returns pointer to a local
> port node, or NULL if graph isn't specified in a device-tree for a given
> device node.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Nice little helper function.
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

Rob - OK to commit to drm-misc-next?

	Sam

> ---
>  drivers/of/property.c    | 32 +++++++++++++++++++++++---------
>  include/linux/of_graph.h |  7 +++++++
>  2 files changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 252e4f600155..5dbeccaabb86 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -608,15 +608,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
>  	 * parent port node.
>  	 */
>  	if (!prev) {
> -		struct device_node *node;
> -
> -		node = of_get_child_by_name(parent, "ports");
> -		if (node)
> -			parent = node;
> -
> -		port = of_get_child_by_name(parent, "port");
> -		of_node_put(node);
> -
> +		port = of_graph_get_local_port(parent);
>  		if (!port) {
>  			pr_err("graph: no port node found in %pOF\n", parent);
>  			return NULL;
> @@ -765,6 +757,28 @@ struct device_node *of_graph_get_remote_port(const struct device_node *node)
>  }
>  EXPORT_SYMBOL(of_graph_get_remote_port);
>  
> +/**
> + * of_graph_get_local_port() - get local port node
> + * @node: pointer to a local endpoint device_node
> + *
> + * Return: First local port node associated with local endpoint node linked
> + *	   to @node. Use of_node_put() on it when done.
> + */
> +struct device_node *of_graph_get_local_port(const struct device_node *node)
> +{
> +	struct device_node *ports, *port;
> +
> +	ports = of_get_child_by_name(node, "ports");
> +	if (ports)
> +		node = ports;
> +
> +	port = of_get_child_by_name(node, "port");
> +	of_node_put(ports);
> +
> +	return port;
> +}
> +EXPORT_SYMBOL(of_graph_get_local_port);
> +
>  int of_graph_get_endpoint_count(const struct device_node *np)
>  {
>  	struct device_node *endpoint;
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index 01038a6aade0..1fdeb72c7765 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -54,6 +54,7 @@ struct device_node *of_graph_get_remote_port_parent(
>  struct device_node *of_graph_get_remote_port(const struct device_node *node);
>  struct device_node *of_graph_get_remote_node(const struct device_node *node,
>  					     u32 port, u32 endpoint);
> +struct device_node *of_graph_get_local_port(const struct device_node *node);
>  #else
>  
>  static inline int of_graph_parse_endpoint(const struct device_node *node,
> @@ -116,6 +117,12 @@ static inline struct device_node *of_graph_get_remote_node(
>  	return NULL;
>  }
>  
> +static inline struct device_node *of_graph_get_local_port(
> +					const struct device_node *node)
> +{
> +	return NULL;
> +}
> +
>  #endif /* CONFIG_OF */
>  
>  #endif /* __LINUX_OF_GRAPH_H */
> -- 
> 2.26.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

On Wed, May 6, 2020 at 11:32 AM Sam Ravnborg <sam@ravnborg.org> wrote:
>
> Hi Dmitry
>
> On Sat, Apr 18, 2020 at 08:06:58PM +0300, Dmitry Osipenko wrote:
> > In some case, like a DRM display code for example, it's useful to silently
> > check whether port node exists at all in a device-tree before proceeding
> > with parsing the graph.
> >
> > This patch adds of_graph_get_local_port() which returns pointer to a local
> > port node, or NULL if graph isn't specified in a device-tree for a given
> > device node.
> >
> > Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> Nice little helper function.
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
>
> Rob - OK to commit to drm-misc-next?

Yes, that's why I gave my R-by.

Rob