diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index e9214de5f3b7..7e8284575dff 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -48,6 +48,9 @@
 #define TB_DP_AUX_PRIORITY		2
 #define TB_DP_AUX_WEIGHT		1
 
+/* struct tb_regs_hop::initial_credits is 7 bits wide */
+#define TB_MAX_CREDITS			127
+
 /* Minimum number of credits needed for PCIe path */
 #define TB_MIN_PCIE_CREDITS		6U
 /*
@@ -1907,7 +1910,7 @@ struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
 	struct tb_tunnel *tunnel;
 	size_t npaths = 0, i = 0;
 	struct tb_path *path;
-	int credits;
+	unsigned int credits;
 
 	/* Ring 0 is reserved for control channel */
 	if (WARN_ON(!receive_ring || !transmit_ring))
@@ -1930,6 +1933,11 @@ struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
 	tunnel->destroy = tb_dma_destroy;
 
 	credits = min_not_zero(dma_credits, nhi->sw->max_dma_credits);
+	if (credits > TB_MAX_CREDITS) {
+		tb_tunnel_dbg(tunnel, "%u credits do not fit a hop, using %u\n",
+			      credits, TB_MAX_CREDITS);
+		credits = TB_MAX_CREDITS;
+	}
 
 	if (receive_ring > 0) {
 		path = tb_path_alloc(tb, dst, receive_path, nhi, receive_ring, 0,