[PATCH v2 02/16] device property: Add fwnode_graph_get_next_port_endpoint()

[Chen-Yu Tsai]

On Wed, Jun 10, 2026 at 11:08 PM Andy Shevchenko
<andriy.shevchenko at linux.intel.com> wrote:
>
> On Wed, Jun 10, 2026 at 04:40:36PM +0800, Chen-Yu Tsai wrote:
> > Due to design constraints of the power sequencing API, the consumer
> > must first be sure that the other side is actually a provider, or it
> > will continually get -EPROBE_DEFER when requesting the power
> > sequencing descriptor.
> >
> > In the upcoming USB power sequencing integration, the USB hub driver
> > first needs to check whether a graph connection exists, and whether
> > the other side of the connection is a supported connector type. The
> > USB port is tied to a "port" firmware node, and this new helper will
> > be used to get the endpoint under the known "port" firmware node.
>
> ...
>
> > +/**
> > + * fwnode_graph_get_next_port_endpoint - Get next endpoint firmware node in port
> > + * @port: Pointer to the target port firmware node
> > + * @prev: Previous endpoint node or %NULL to get the first
> > + *
> > + * The caller is responsible for calling fwnode_handle_put() on the returned
> > + * fwnode pointer. Note that this function also puts a reference to @prev
> > + * unconditionally.
> > + *
> > + * Return: an endpoint firmware node pointer or %NULL if no more endpoints
> > + * are available.
>
> Yeah, you see, even here is inconsistency with previously added kernel-doc.
>
> > + */
> > +struct fwnode_handle *fwnode_graph_get_next_port_endpoint(const struct fwnode_handle *port,
> > +                                                       struct fwnode_handle *prev)
> > +{
> > +     struct fwnode_handle *ep;
>
> Unused?
>
> > +     while (1) {
>
> This is usually harder to read and follow. It's like "pay much attention on
> the code", but here no rocket science, no code to really pay attention to.
>
> > +             prev = fwnode_get_next_child_node(port, prev);
> > +             if (!prev)
> > +                     break;
> > +
> > +             if (WARN(!fwnode_name_eq(prev, "endpoint"),
> > +                      "non endpoint node is used (%pfw)", prev))
> > +                     continue;
> > +
> > +             break;
> > +     }
> > +
> > +     return prev;
> > +}
>
> So, this can be rewritten as
>
>         ep = prev;
>         do {
>                 ep = fwnode_get_next_child_node(port, ep);
>                 if (fwnode_name_eq(ep, "endpoint"))
>                         break;
>
>                 WARN_ON(ep, ...);
>         } while (ep);
>
>         return ep;
>
> But also big question why? to WARN*(). There is no use in the entire
> property.c.

Will drop. This function was lifted from drivers/of/property.c then
adapted to the fwnode APIs, so it still has the structure of its
origin. With the WARN() gone, rewriting it as do {} while() becomes:

do {
        prev = fwnode_get_next_child_node(port, prev);
        if (prev && fwnode_name_eq(prev, "endpoint"))
                break;
} while (prev);

return prev;


Thanks
ChenYu