[PATCH] checks: Remove check for graph child addresses

[PATCH] checks: Remove check for graph child addresses

[Niklas Söderlund]

The dtc graph_child_address check can't distinguish between bindings
where there can only be a single endpoint, and cases where there can be
multiple endpoints.

In cases where the bindings allow for multiple endpoints but only one is
described false warnings about unnecessary #address-cells/#size-cells
can be generated, but only if the endpoint described have an address of
0 (A), for single endpoints with a non-zero address (B) no warnings are
generated.

A)
    ports {
	#address-cells = <1>;
	#size-cells = <0>;

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

	    sourceA: endpoint@0 {
		reg = <0>
	    };
	};
    };

B)
    ports {
	#address-cells = <1>;
	#size-cells = <0>;

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

	    sourceB: endpoint@1 {
		reg = <1>
	    };
	};
    };

Remove the check as it is somewhat redundant now that we can use schemas
to validate the full node.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
Hello,

This started as an effort to demote this check to W=2 [1] and have then
moved on from there to completely remove the check in this patch per
David and Rob's suggestion.

This patch supersedes all other patches for my me in this area.

If this change is accepted in dtc and later checks.c synced to
linux/scripts/dtc/checks.c one must also drop "-Wno-graph_child_address"
from Documentation/devicetree/bindings/Makefile and
scripts/Makefile.dtbs.

1.  https://lore.kernel.org/all/20250702085008.689727-1-niklas.soderlund%2Brenesas@ragnatech.se/
---
 checks.c | 27 +--------------------------
 1 file changed, 1 insertion(+), 26 deletions(-)

diff --git a/checks.c b/checks.c
index 123f2eb425f4..0b1fd9f13cb4 100644
--- a/checks.c
+++ b/checks.c
@@ -1894,31 +1894,6 @@ static void check_graph_endpoint(struct check *c, struct dt_info *dti,
 }
 WARNING(graph_endpoint, check_graph_endpoint, NULL, &graph_nodes);
 
-static void check_graph_child_address(struct check *c, struct dt_info *dti,
-				      struct node *node)
-{
-	int cnt = 0;
-	struct node *child;
-
-	if (node->bus != &graph_ports_bus && node->bus != &graph_port_bus)
-		return;
-
-	for_each_child(node, child) {
-		struct property *prop = get_property(child, "reg");
-
-		/* No error if we have any non-zero unit address */
-                if (prop && propval_cell(prop) != 0 )
-			return;
-
-		cnt++;
-	}
-
-	if (cnt == 1 && node->addr_cells != -1)
-		FAIL(c, dti, node, "graph node has single child node '%s', #address-cells/#size-cells are not necessary",
-		     node->children->name);
-}
-WARNING(graph_child_address, check_graph_child_address, NULL, &graph_nodes, &graph_port, &graph_endpoint);
-
 static struct check *check_table[] = {
 	&duplicate_node_names, &duplicate_property_names,
 	&node_name_chars, &node_name_format, &property_name_chars,
@@ -2005,7 +1980,7 @@ static struct check *check_table[] = {
 
 	&alias_paths,
 
-	&graph_nodes, &graph_child_address, &graph_port, &graph_endpoint,
+	&graph_nodes, &graph_port, &graph_endpoint,
 
 	&always_fail,
 };
-- 
2.50.0