thunderbolt: Introduce tb_port_path_direction_downstream()

Introduce tb_port_path_direction_downstream() to check if path from
source adapter to destination adapter is directed towards downstream.
Convert existing users to call this helper instead of open-coding.

No functional changes.

Signed-off-by: Gil Fine <gil.fine@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 3c9ae5584569..6d49510eea09 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1041,6 +1041,21 @@ void tb_port_release_out_hopid(struct tb_port *port, int hopid);
 struct tb_port *tb_next_port_on_path(struct tb_port *start, struct tb_port *end,
 				     struct tb_port *prev);
 
+/**
+ * tb_port_path_direction_downstream() - Checks if path directed downstream
+ * @src: Source adapter
+ * @dst: Destination adapter
+ *
+ * Returns %true only if the specified path from source adapter (@src)
+ * to destination adapter (@dst) is directed downstream.
+ */
+static inline bool
+tb_port_path_direction_downstream(const struct tb_port *src,
+				  const struct tb_port *dst)
+{
+	return src->sw->config.depth < dst->sw->config.depth;
+}
+
 static inline bool tb_port_use_credit_allocation(const struct tb_port *port)
 {
 	return tb_port_is_null(port) && port->sw->credit_allocation;