device property: Check fwnode->secondary in fwnode_graph_get_next_endpoint()

Sensor drivers often check for an endpoint to make sure that they're
connected to a consuming device like a CIO2 during .probe(). Some of
those endpoints might be in the form of software_nodes assigned as
a secondary to the device's fwnode_handle. Account for this possibility
in fwnode_graph_get_next_endpoint() to avoid having to do it in the
sensor drivers themselves.
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NDaniel Scally <djrscally@gmail.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/property.c

@@ -1033,7 +1033,26 @@ struct fwnode_handle *
 fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
 			       struct fwnode_handle *prev)
 {
-	return fwnode_call_ptr_op(fwnode, graph_get_next_endpoint, prev);
+	const struct fwnode_handle *parent;
+	struct fwnode_handle *ep;
+
+	/*
+	 * If this function is in a loop and the previous iteration returned
+	 * an endpoint from fwnode->secondary, then we need to use the secondary
+	 * as parent rather than @fwnode.
+	 */
+	if (prev)
+		parent = fwnode_graph_get_port_parent(prev);
+	else
+		parent = fwnode;
+
+	ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev);
+
+	if (IS_ERR_OR_NULL(ep) &&
+	    !IS_ERR_OR_NULL(parent) && !IS_ERR_OR_NULL(parent->secondary))
+		ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL);
+
+	return ep;
 }
 EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);