Hi Morimoto-san,
On Mon, Jan 29, 2024 at 12:54:59AM +0000, Kuninori Morimoto wrote:
> We already have of_graph_get_next_endpoint(), but it is not intuitive
> to use.
>
> (X) node {
> (Y) ports {
> port@0 { endpoint { remote-endpoint = ...; };};
> (A1) port@1 { endpoint { remote-endpoint = ...; };
> (A2) endpoint { remote-endpoint = ...; };};
> (B) port@2 { endpoint { remote-endpoint = ...; };};
> };
> };
>
> For example, if I want to handle port@1's 2 endpoints (= A1, A2),
> I want to use like below
>
> A1 = of_graph_get_next_endpoint(port1, NULL);
> A2 = of_graph_get_next_endpoint(port1, A1);
>
> But 1st one will be error, because of_graph_get_next_endpoint() requested
> "parent" means "node" (X) or "ports" (Y), not "port".
> Below are OK
>
> of_graph_get_next_endpoint(node, NULL); // node/ports/port@0/endpoint
> of_graph_get_next_endpoint(ports, NULL); // node/ports/port@0/endpoint
>
> In other words, we can't handle A1/A2 directly via
> of_graph_get_next_endpoint() so far.
>
> There is another non intuitive behavior on of_graph_get_next_endpoint().
> In case of if I could get A1 pointer for some way, and if I want to
> handle port@1 things, I would like use it like below
>
> /*
> * "endpoint" is now A1, and handle port1 things here,
> * but we don't know how many endpoints port1 has.
> *
> * Because "endpoint" is non NULL, we can use port1
> * as of_graph_get_next_endpoint(port1, xxx)
> */
> do {
> /* do something for port1 specific things here */
> } while (endpoint = of_graph_get_next_endpoint(port1, endpoint))
>
> But it also not worked as I expected.
> I expect it will be A1 -> A2 -> NULL,
> but it will be A1 -> A2 -> B, because of_graph_get_next_endpoint()
> will fetch endpoint beyond the port.
>
> It is not useful on generic driver like Generic Sound Card.
> It uses of_get_next_child() instead for now, but it is not intuitive,
> and not check node name (= "endpoint").
>
> To handle endpoint more intuitive, create of_graph_get_next_endpoint_raw()
>
> of_graph_get_next_endpoint_raw(port1, NULL); // A1
> of_graph_get_next_endpoint_raw(port1, A1); // A2
> of_graph_get_next_endpoint_raw(port1, A2); // NULL
>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> ---
> drivers/of/property.c | 26 +++++++++++++++++++++++++-
> include/linux/of_graph.h | 2 ++
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 14ffd199c9b1..37dbb1b0e742 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -667,6 +667,30 @@ struct device_node *of_graph_get_next_port(const struct device_node *parent,
> }
> EXPORT_SYMBOL(of_graph_get_next_port);
>
> +/**
> + * of_graph_get_next_endpoint_raw() - get next endpoint node
> + * @port: pointer to the target port node
> + * @endpoint: current endpoint node, or NULL to get first
> + *
> + * Return: An 'endpoint' node pointer with refcount incremented. Refcount
> + * of the passed @prev node is decremented.
> + */
> +struct device_node *of_graph_get_next_endpoint_raw(const struct device_node *port,
> + struct device_node *endpoint)
> +{
> + if (!port)
> + return NULL;
of_get_next_child() returns NULL if node is NULL, hence there's no need to
check this.
> +
> + do {
> + endpoint = of_get_next_child(port, endpoint);
> + if (!endpoint)
> + break;
> + } while (!of_node_name_eq(endpoint, "endpoint"));
> +
> + return endpoint;
> +}
> +EXPORT_SYMBOL(of_graph_get_next_endpoint_raw);
> +
> /**
> * of_graph_get_next_endpoint() - get next endpoint node
> * @parent: pointer to the parent device node
> @@ -708,7 +732,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
> * getting the next child. If the previous endpoint is NULL this
> * will return the first child.
> */
> - endpoint = of_get_next_child(port, prev);
> + endpoint = of_graph_get_next_endpoint_raw(port, prev);
> if (endpoint) {
> of_node_put(port);
> return endpoint;
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index fff598640e93..427905a6e8c3 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -57,6 +57,8 @@ int of_graph_get_port_count(const struct device_node *np);
> struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
> struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
> struct device_node *previous);
> +struct device_node *of_graph_get_next_endpoint_raw(const struct device_node *port,
> + struct device_node *prev);
> struct device_node *of_graph_get_next_port(const struct device_node *parent,
> struct device_node *previous);
> struct device_node *of_graph_get_endpoint_by_regs(
--
Kind regards,
Sakari Ailus
