Re: [PATCH] checks: Remove check for graph child addresses

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

Hello,

This was sent to the wrong list, please ignore it. I have resent it to 
the correct devicetree-compiler@vger.kernel.org list.

Sorry for the noise.

On 2025-07-08 18:02:01 +0200, Niklas Söderlund wrote:
> 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
> 

-- 
Kind Regards,
Niklas Söderlund