thunderbolt: Assign remote for both ports in case of dual link

Currently the driver only assigns remote port for the primary port if in
case of dual link. This makes things such as walking from one port to
another more complex than necessary because the code needs to change
from secondary to primary port if the path that is established is
created using secondary links.

In order to always assign both remote pointers we need to prevent the
scanning code from following the secondary link. Failing to do that
might cause problems as the same switch may be enumerated twice (or
removed in case of unplug). Handle that properly by introducing a new
function tb_port_has_remote() that returns true only for the primary
port. We also update tb_is_upstream_port() to support both dual link
ports, make it take const port pointer and move it below
tb_upstream_port() to keep similar functions close.

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

1 files changed, 31 insertions, 5 deletions

diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 1cb5009195f9..43bc4f490021 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -270,6 +270,19 @@ static inline struct tb_port *tb_upstream_port(struct tb_switch *sw)
 	return &sw->ports[sw->config.upstream_port_number];
 }
 
+/**
+ * tb_is_upstream_port() - Is the port upstream facing
+ * @port: Port to check
+ *
+ * Returns true if @port is upstream facing port. In case of dual link
+ * ports both return true.
+ */
+static inline bool tb_is_upstream_port(const struct tb_port *port)
+{
+	const struct tb_port *upstream_port = tb_upstream_port(port->sw);
+	return port == upstream_port || port->dual_link_port == upstream_port;
+}
+
 static inline u64 tb_route(struct tb_switch *sw)
 {
 	return ((u64) sw->config.route_hi) << 32 | sw->config.route_lo;
@@ -285,6 +298,24 @@ static inline struct tb_port *tb_port_at(u64 route, struct tb_switch *sw)
 	return &sw->ports[port];
 }
 
+/**
+ * tb_port_has_remote() - Does the port have switch connected downstream
+ * @port: Port to check
+ *
+ * Returns true only when the port is primary port and has remote set.
+ */
+static inline bool tb_port_has_remote(const struct tb_port *port)
+{
+	if (tb_is_upstream_port(port))
+		return false;
+	if (!port->remote)
+		return false;
+	if (port->dual_link_port && port->link_nr)
+		return false;
+
+	return true;
+}
+
 static inline int tb_sw_read(struct tb_switch *sw, void *buffer,
 			     enum tb_cfg_space space, u32 offset, u32 length)
 {
@@ -489,11 +520,6 @@ static inline int tb_route_length(u64 route)
 	return (fls64(route) + TB_ROUTE_SHIFT - 1) / TB_ROUTE_SHIFT;
 }
 
-static inline bool tb_is_upstream_port(struct tb_port *port)
-{
-	return port == tb_upstream_port(port->sw);
-}
-
 /**
  * tb_downstream_route() - get route to downstream switch
  *