Hi Dmitry,
Thank you for the patch.
On Wed, Jul 01, 2020 at 05:16:16AM +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 of the graph.
>
> This patch adds of_graph_is_present() which returns true if given
> device-tree node contains OF graph port.
>
> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++-------
> include/linux/of_graph.h | 6 +++++
> 2 files changed, 49 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 6a5760f0d6cd..e12b8b491837 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -29,6 +29,48 @@
>
> #include "of_private.h"
>
> +/**
> + * of_graph_get_first_local_port() - get first local port node
> + * @node: pointer to a local endpoint device_node
It's not an endpoint.
> + *
> + * Return: First local port node associated with local endpoint node linked
> + * to @node. Use of_node_put() on it when done.
> + */
> +static struct device_node *
> +of_graph_get_first_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;
> +}
> +
> +/**
> + * of_graph_is_present() - check graph's presence
> + * @node: pointer to a device_node checked for the graph's presence
> + *
> + * Return: True if @node has a port or ports sub-node, false otherwise.
> + */
> +bool of_graph_is_present(const struct device_node *node)
> +{
> + struct device_node *local;
> +
> + local = of_graph_get_first_local_port(node);
> + if (!local)
> + return false;
> +
> + of_node_put(local);
> +
> + return true;
> +}
> +EXPORT_SYMBOL(of_graph_is_present);
> +
> /**
> * of_property_count_elems_of_size - Count the number of elements in a property
> *
> @@ -608,15 +650,7 @@ 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_first_local_port(parent);
I think this introduces a bug below in the function, where parent is
used and is expected to point to the ports node if available. I'd leave
this part of the change out, and inline +of_graph_get_first_local_port()
in of_graph_is_present().
> if (!port) {
> pr_err("graph: no port node found in %pOF\n", parent);
> return NULL;
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index 01038a6aade0..4d7756087b6b 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -38,6 +38,7 @@ struct of_endpoint {
> child = of_graph_get_next_endpoint(parent, child))
>
> #ifdef CONFIG_OF
> +bool of_graph_is_present(const struct device_node *node);
> int of_graph_parse_endpoint(const struct device_node *node,
> struct of_endpoint *endpoint);
> int of_graph_get_endpoint_count(const struct device_node *np);
> @@ -56,6 +57,11 @@ struct device_node *of_graph_get_remote_node(const struct device_node *node,
> u32 port, u32 endpoint);
> #else
>
> +static inline bool of_graph_is_present(const struct device_node *node)
> +{
> + return false;
> +}
> +
> static inline int of_graph_parse_endpoint(const struct device_node *node,
> struct of_endpoint *endpoint)
> {
--
Regards,
Laurent Pinchart
