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@kernel.org Signed-off-by: Dmitry Osipenko digetx@gmail.com

---

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) {