Re: [PATCH v3 1/6] device property: Helper to match multiple connections

Andy Shevchenko
2022-03-04T12:55:15Z

On Thu, Mar 03, 2022 at 02:33:46PM -0800, Bjorn Andersson wrote:
> In some cases multiple connections with the same connection id
> needs to be resolved from a fwnode graph.
>
> One such example is when separate hardware is used for performing muxing
> and/or orientation switching of the SuperSpeed and SBU lines in a USB
> Type-C connector. In this case the connector needs to belong to a graph
> with multiple matching remote endpoints, and the Type-C controller needs
> to be able to resolve them both.
>
> Add a new API that allows this kind of lookup.

...

> +static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
> + const char *con_id, void *data,
> + devcon_match_fn_t match,
> + void **matches,
> + unsigned int matches_len)
> +{
> + struct fwnode_handle *node;
> + struct fwnode_handle *ep;
> + unsigned int count = 0;
> + void *ret;
> +
> + fwnode_graph_for_each_endpoint(fwnode, ep) {

> + if (count >= matches_len && matches) {
> + fwnode_handle_put(ep);
> + return count;
> + }

Wouldn't be the same as

if (count >= matches_len) {
fwnode_handle_put(ep);
break;
}

?

> + node = fwnode_graph_get_remote_port_parent(ep);
> + if (!fwnode_device_is_available(node)) {
> + fwnode_handle_put(node);
> + continue;
> + }
> +
> + ret = match(node, con_id, data);
> + fwnode_handle_put(node);
> + if (ret) {
> + if (matches)
> + matches[count] = ret;
> + count++;
> + }
> + }
> + return count;
> +}

...

> +static unsigned int fwnode_devcon_matches(struct fwnode_handle *fwnode,
> + const char *con_id, void *data,
> + devcon_match_fn_t match,
> + void **matches,
> + unsigned int matches_len)
> +{
> + struct fwnode_handle *node;
> + unsigned int count = 0;
> + unsigned int i;
> + void *ret;
> +
> + for (i = 0; ; i++) {

> + if (count >= matches_len && matches)
> + return count;

Ditto.

> + node = fwnode_find_reference(fwnode, con_id, i);
> + if (IS_ERR(node))
> + break;
> +
> + ret = match(node, NULL, data);
> + fwnode_handle_put(node);
> + if (ret) {
> + if (matches)
> + matches[count] = ret;
> + count++;
> + }
> + }
> +
> + return count;
> +}

...

> +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
> + const char *con_id, void *data,
> + devcon_match_fn_t match,
> + void **matches, unsigned int matches_len)
> +{
> + unsigned int count_graph;
> + unsigned int count_ref;
> +
> + if (!fwnode || !match)
> + return -EINVAL;

> + count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
> + matches, matches_len);

> + matches += count_graph;
> + matches_len -= count_graph;

No, won't work when matches == NULL.

Also, matches_len is expected to be 0 in that case (or at least being ignored,
check with vsnprintf() behaviour in similar case).

So, something like this, perhaps

if (matches && matches_len) {
matches += count_graph;
matches_len -= count_graph;
}

> + count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
> + matches, matches_len);
> +
> + return count_graph + count_ref;
> +}

--
With Best Regards,
Andy Shevchenko