Re: [PATCH 1/2] of: Add helper to lookup non port child node

On Mon, Dec 6, 2021 at 11:49 PM Jagan Teki jagan@amarulasolutions.com wrote:

Add of_get_non_port_child() helper that can be used to lookup non port child nodes.

Some OF graphs don't require 'ports' to represent the next output instead, it simply adds a child node on a given parent node. This helper lookup that child node, however that child node is not a 'port' on given parent as 'port' based nodes are looked up via of_graph_get_remote_node().

Example OF graph representation of DSI host, which doesn't have 'ports'.

This seems pretty specific to DSI and also can't handle there being more than 1 non-port node. That's allowed for DSI too, but I don't think I've ever seen a case. Anyways, I'd just move this to DRM rather than common DT code. One comment on the implementation that will shrink it.

dsi { #address-cells = <1>; #size-cells = <0>;

    port {
            dsi_in_tcon0: endpoint {
                    remote-endpoint = <tcon0_out_dsi>;
    };

    panel@0 {
            reg = <0>;
    };

};

Signed-off-by: Jagan Teki jagan@amarulasolutions.com

drivers/of/base.c | 29 +++++++++++++++++++++++++++++ include/linux/of.h | 6 ++++++ 2 files changed, 35 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c index 61de453b885c..31bbf885b0f8 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -854,6 +854,35 @@ struct device_node *of_get_compatible_child(const struct device_node *parent, } EXPORT_SYMBOL(of_get_compatible_child);

+/**

• • of_get_non_port_child - Find the non port child node for a given parent
• • @node: parent node
• • This function looks for child node which is not port child for given parent.
• • Return: A node pointer if found, with refcount incremented, use
• • of_node_put() on it when done.
• • Returns NULL if node is not found.
• */

+struct device_node *of_get_non_port_child(const struct device_node *parent) +{

•   struct device_node *child;
  

•   for_each_child_of_node(parent, child) {
  

for_each_available_child_of_node

•           if (of_node_name_eq(child, "port"))
  

•                   continue;
  

•           if (!of_device_is_available(child)) {
  

•                   of_node_put(child);
  

•                   continue;
  

•           }
  

•           break;
  

•   }
  

•   return child;
  

+} +EXPORT_SYMBOL(of_get_non_port_child);

/**

• of_get_child_by_name - Find the child node by name for a given parent
• @node: parent node

diff --git a/include/linux/of.h b/include/linux/of.h index ff143a027abc..3e699becef82 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -290,6 +290,7 @@ extern struct device_node *of_get_next_child(const struct device_node *node, extern struct device_node *of_get_next_available_child( const struct device_node *node, struct device_node *prev);

+extern struct device_node *of_get_non_port_child(const struct device_node *parent); extern struct device_node *of_get_compatible_child(const struct device_node *parent, const char *compatible); extern struct device_node *of_get_child_by_name(const struct device_node *node, @@ -678,6 +679,11 @@ static inline bool of_have_populated_dt(void) return false; }

+static inline struct device_node *of_get_non_port_child(const struct device_node *parent) +{

•   return NULL;
  

+}

static inline struct device_node *of_get_compatible_child(const struct device_node *parent, const char *compatible) { -- 2.25.1