1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index bd211e97ee4b..825cc2f4d8ef 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -1173,14 +1173,15 @@ static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
  * @dst_port: Destination adapter
  * @requested_up: New lower bandwidth request upstream (Mb/s)
  * @requested_down: New lower bandwidth request downstream (Mb/s)
+ * @keep_asym: Keep asymmetric link if preferred
  *
  * Goes over each link from @src_port to @dst_port and tries to
  * transition the link to symmetric if the currently consumed bandwidth
- * allows.
+ * allows and link asymmetric preference is ignored (if @keep_asym is %false).
  */
 static int tb_configure_sym(struct tb *tb, struct tb_port *src_port,
 			    struct tb_port *dst_port, int requested_up,
-			    int requested_down)
+			    int requested_down, bool keep_asym)
 {
 	bool clx = false, clx_disabled = false, downstream;
 	struct tb_switch *sw;
@@ -1229,6 +1230,19 @@ static int tb_configure_sym(struct tb *tb, struct tb_port *src_port,
 		if (up->sw->link_width == TB_LINK_WIDTH_DUAL)
 			continue;
 
+		/*
+		 * Here consumed < threshold so we can transition the
+		 * link to symmetric.
+		 *
+		 * However, if the router prefers asymmetric link we
+		 * honor that (unless @keep_asym is %false).
+		 */
+		if (keep_asym &&
+		    up->sw->preferred_link_width > TB_LINK_WIDTH_DUAL) {
+			tb_sw_dbg(up->sw, "keeping preferred asymmetric link\n");
+			continue;
+		}
+
 		/* Disable CL states before doing any transitions */
 		if (!clx_disabled) {
 			clx = tb_disable_clx(sw);
@@ -1282,7 +1296,7 @@ static void tb_configure_link(struct tb_port *down, struct tb_port *up,
 		struct tb_port *host_port;
 
 		host_port = tb_port_at(tb_route(sw), tb->root_switch);
-		tb_configure_sym(tb, host_port, up, 0, 0);
+		tb_configure_sym(tb, host_port, up, 0, 0, false);
 	}
 
 	/* Set the link configured */
@@ -1467,7 +1481,7 @@ static void tb_deactivate_and_free_tunnel(struct tb_tunnel *tunnel)
 		 * If bandwidth on a link is < asym_threshold
 		 * transition the link to symmetric.
 		 */
-		tb_configure_sym(tb, src_port, dst_port, 0, 0);
+		tb_configure_sym(tb, src_port, dst_port, 0, 0, true);
 		/* Now we can allow the domain to runtime suspend again */
 		pm_runtime_mark_last_busy(&dst_port->sw->dev);
 		pm_runtime_put_autosuspend(&dst_port->sw->dev);
@@ -2289,7 +2303,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 		 * If bandwidth on a link is < asym_threshold transition
 		 * the link to symmetric.
 		 */
-		tb_configure_sym(tb, in, out, *requested_up, *requested_down);
+		tb_configure_sym(tb, in, out, *requested_up, *requested_down, true);
 		/*
 		 * If requested bandwidth is less or equal than what is
 		 * currently allocated to that tunnel we simply change
@@ -2332,7 +2346,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 		ret = tb_configure_asym(tb, in, out, *requested_up,
 					*requested_down);
 		if (ret) {
-			tb_configure_sym(tb, in, out, 0, 0);
+			tb_configure_sym(tb, in, out, 0, 0, true);
 			return ret;
 		}
 
@@ -2340,7 +2354,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 						requested_down);
 		if (ret) {
 			tb_tunnel_warn(tunnel, "failed to allocate bandwidth\n");
-			tb_configure_sym(tb, in, out, 0, 0);
+			tb_configure_sym(tb, in, out, 0, 0, true);
 		}
 	} else {
 		ret = -ENOBUFS;