Merging upstream version 6.7.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 628 insertions, 156 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 27bd6ca6f9..fd49f86e03 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -16,8 +16,31 @@
 #include "tb_regs.h"
 #include "tunnel.h"
 
-#define TB_TIMEOUT	100	/* ms */
-#define MAX_GROUPS	7	/* max Group_ID is 7 */
+#define TB_TIMEOUT		100	/* ms */
+
+/*
+ * Minimum bandwidth (in Mb/s) that is needed in the single transmitter/receiver
+ * direction. This is 40G - 10% guard band bandwidth.
+ */
+#define TB_ASYM_MIN		(40000 * 90 / 100)
+
+/*
+ * Threshold bandwidth (in Mb/s) that is used to switch the links to
+ * asymmetric and back. This is selected as 45G which means when the
+ * request is higher than this, we switch the link to asymmetric, and
+ * when it is less than this we switch it back. The 45G is selected so
+ * that we still have 27G (of the total 72G) for bulk PCIe traffic when
+ * switching back to symmetric.
+ */
+#define TB_ASYM_THRESHOLD	45000
+
+#define MAX_GROUPS		7	/* max Group_ID is 7 */
+
+static unsigned int asym_threshold = TB_ASYM_THRESHOLD;
+module_param_named(asym_threshold, asym_threshold, uint, 0444);
+MODULE_PARM_DESC(asym_threshold,
+		"threshold (Mb/s) when to Gen 4 switch link symmetry. 0 disables. (default: "
+		__MODULE_STRING(TB_ASYM_THRESHOLD) ")");
 
 /**
  * struct tb_cm - Simple Thunderbolt connection manager
@@ -190,7 +213,17 @@ static void tb_add_dp_resources(struct tb_switch *sw)
 		if (!tb_switch_query_dp_resource(sw, port))
 			continue;
 
-		list_add_tail(&port->list, &tcm->dp_resources);
+		/*
+		 * If DP IN on device router exist, position it at the
+		 * beginning of the DP resources list, so that it is used
+		 * before DP IN of the host router. This way external GPU(s)
+		 * will be prioritized when pairing DP IN to a DP OUT.
+		 */
+		if (tb_route(sw))
+			list_add(&port->list, &tcm->dp_resources);
+		else
+			list_add_tail(&port->list, &tcm->dp_resources);
+
 		tb_port_dbg(port, "DP IN resource available\n");
 	}
 }
@@ -255,13 +288,13 @@ static int tb_enable_clx(struct tb_switch *sw)
 	 * this in the future to cover the whole topology if it turns
 	 * out to be beneficial.
 	 */
-	while (sw && sw->config.depth > 1)
+	while (sw && tb_switch_depth(sw) > 1)
 		sw = tb_switch_parent(sw);
 
 	if (!sw)
 		return 0;
 
-	if (sw->config.depth != 1)
+	if (tb_switch_depth(sw) != 1)
 		return 0;
 
 	/*
@@ -285,14 +318,32 @@ static int tb_enable_clx(struct tb_switch *sw)
 	return ret == -EOPNOTSUPP ? 0 : ret;
 }
 
-/* Disables CL states up to the host router */
-static void tb_disable_clx(struct tb_switch *sw)
+/**
+ * tb_disable_clx() - Disable CL states up to host router
+ * @sw: Router to start
+ *
+ * Disables CL states from @sw up to the host router. Returns true if
+ * any CL state were disabled. This can be used to figure out whether
+ * the link was setup by us or the boot firmware so we don't
+ * accidentally enable them if they were not enabled during discovery.
+ */
+static bool tb_disable_clx(struct tb_switch *sw)
 {
+	bool disabled = false;
+
 	do {
-		if (tb_switch_clx_disable(sw) < 0)
+		int ret;
+
+		ret = tb_switch_clx_disable(sw);
+		if (ret > 0)
+			disabled = true;
+		else if (ret < 0)
 			tb_sw_warn(sw, "failed to disable CL states\n");
+
 		sw = tb_switch_parent(sw);
 	} while (sw);
+
+	return disabled;
 }
 
 static int tb_increase_switch_tmu_accuracy(struct device *dev, void *data)
@@ -553,7 +604,7 @@ static struct tb_tunnel *tb_find_first_usb3_tunnel(struct tb *tb,
 	struct tb_switch *sw;
 
 	/* Pick the router that is deepest in the topology */
-	if (dst_port->sw->config.depth > src_port->sw->config.depth)
+	if (tb_port_path_direction_downstream(src_port, dst_port))
 		sw = dst_port->sw;
 	else
 		sw = src_port->sw;
@@ -572,133 +623,294 @@ static struct tb_tunnel *tb_find_first_usb3_tunnel(struct tb *tb,
 	return tb_find_tunnel(tb, TB_TUNNEL_USB3, usb3_down, NULL);
 }
 
-static int tb_available_bandwidth(struct tb *tb, struct tb_port *src_port,
-	struct tb_port *dst_port, int *available_up, int *available_down)
-{
-	int usb3_consumed_up, usb3_consumed_down, ret;
-	struct tb_cm *tcm = tb_priv(tb);
+/**
+ * tb_consumed_usb3_pcie_bandwidth() - Consumed USB3/PCIe bandwidth over a single link
+ * @tb: Domain structure
+ * @src_port: Source protocol adapter
+ * @dst_port: Destination protocol adapter
+ * @port: USB4 port the consumed bandwidth is calculated
+ * @consumed_up: Consumed upsream bandwidth (Mb/s)
+ * @consumed_down: Consumed downstream bandwidth (Mb/s)
+ *
+ * Calculates consumed USB3 and PCIe bandwidth at @port between path
+ * from @src_port to @dst_port. Does not take tunnel starting from
+ * @src_port and ending from @src_port into account.
+ */
+static int tb_consumed_usb3_pcie_bandwidth(struct tb *tb,
+					   struct tb_port *src_port,
+					   struct tb_port *dst_port,
+					   struct tb_port *port,
+					   int *consumed_up,
+					   int *consumed_down)
+{
+	int pci_consumed_up, pci_consumed_down;
 	struct tb_tunnel *tunnel;
-	struct tb_port *port;
 
-	tb_dbg(tb, "calculating available bandwidth between %llx:%u <-> %llx:%u\n",
-	       tb_route(src_port->sw), src_port->port, tb_route(dst_port->sw),
-	       dst_port->port);
+	*consumed_up = *consumed_down = 0;
 
 	tunnel = tb_find_first_usb3_tunnel(tb, src_port, dst_port);
 	if (tunnel && tunnel->src_port != src_port &&
 	    tunnel->dst_port != dst_port) {
-		ret = tb_tunnel_consumed_bandwidth(tunnel, &usb3_consumed_up,
-						   &usb3_consumed_down);
+		int ret;
+
+		ret = tb_tunnel_consumed_bandwidth(tunnel, consumed_up,
+						   consumed_down);
 		if (ret)
 			return ret;
-	} else {
-		usb3_consumed_up = 0;
-		usb3_consumed_down = 0;
 	}
 
-	/* Maximum possible bandwidth asymmetric Gen 4 link is 120 Gb/s */
-	*available_up = *available_down = 120000;
+	/*
+	 * If there is anything reserved for PCIe bulk traffic take it
+	 * into account here too.
+	 */
+	if (tb_tunnel_reserved_pci(port, &pci_consumed_up, &pci_consumed_down)) {
+		*consumed_up += pci_consumed_up;
+		*consumed_down += pci_consumed_down;
+	}
 
-	/* Find the minimum available bandwidth over all links */
-	tb_for_each_port_on_path(src_port, dst_port, port) {
-		int link_speed, link_width, up_bw, down_bw;
+	return 0;
+}
 
-		if (!tb_port_is_null(port))
+/**
+ * tb_consumed_dp_bandwidth() - Consumed DP bandwidth over a single link
+ * @tb: Domain structure
+ * @src_port: Source protocol adapter
+ * @dst_port: Destination protocol adapter
+ * @port: USB4 port the consumed bandwidth is calculated
+ * @consumed_up: Consumed upsream bandwidth (Mb/s)
+ * @consumed_down: Consumed downstream bandwidth (Mb/s)
+ *
+ * Calculates consumed DP bandwidth at @port between path from @src_port
+ * to @dst_port. Does not take tunnel starting from @src_port and ending
+ * from @src_port into account.
+ */
+static int tb_consumed_dp_bandwidth(struct tb *tb,
+				    struct tb_port *src_port,
+				    struct tb_port *dst_port,
+				    struct tb_port *port,
+				    int *consumed_up,
+				    int *consumed_down)
+{
+	struct tb_cm *tcm = tb_priv(tb);
+	struct tb_tunnel *tunnel;
+	int ret;
+
+	*consumed_up = *consumed_down = 0;
+
+	/*
+	 * Find all DP tunnels that cross the port and reduce
+	 * their consumed bandwidth from the available.
+	 */
+	list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
+		int dp_consumed_up, dp_consumed_down;
+
+		if (tb_tunnel_is_invalid(tunnel))
 			continue;
 
-		if (tb_is_upstream_port(port)) {
-			link_speed = port->sw->link_speed;
+		if (!tb_tunnel_is_dp(tunnel))
+			continue;
+
+		if (!tb_tunnel_port_on_path(tunnel, port))
+			continue;
+
+		/*
+		 * Ignore the DP tunnel between src_port and dst_port
+		 * because it is the same tunnel and we may be
+		 * re-calculating estimated bandwidth.
+		 */
+		if (tunnel->src_port == src_port &&
+		    tunnel->dst_port == dst_port)
+			continue;
+
+		ret = tb_tunnel_consumed_bandwidth(tunnel, &dp_consumed_up,
+						   &dp_consumed_down);
+		if (ret)
+			return ret;
+
+		*consumed_up += dp_consumed_up;
+		*consumed_down += dp_consumed_down;
+	}
+
+	return 0;
+}
+
+static bool tb_asym_supported(struct tb_port *src_port, struct tb_port *dst_port,
+			      struct tb_port *port)
+{
+	bool downstream = tb_port_path_direction_downstream(src_port, dst_port);
+	enum tb_link_width width;
+
+	if (tb_is_upstream_port(port))
+		width = downstream ? TB_LINK_WIDTH_ASYM_RX : TB_LINK_WIDTH_ASYM_TX;
+	else
+		width = downstream ? TB_LINK_WIDTH_ASYM_TX : TB_LINK_WIDTH_ASYM_RX;
+
+	return tb_port_width_supported(port, width);
+}
+
+/**
+ * tb_maximum_bandwidth() - Maximum bandwidth over a single link
+ * @tb: Domain structure
+ * @src_port: Source protocol adapter
+ * @dst_port: Destination protocol adapter
+ * @port: USB4 port the total bandwidth is calculated
+ * @max_up: Maximum upstream bandwidth (Mb/s)
+ * @max_down: Maximum downstream bandwidth (Mb/s)
+ * @include_asym: Include bandwidth if the link is switched from
+ *		  symmetric to asymmetric
+ *
+ * Returns maximum possible bandwidth in @max_up and @max_down over a
+ * single link at @port. If @include_asym is set then includes the
+ * additional banwdith if the links are transitioned into asymmetric to
+ * direction from @src_port to @dst_port.
+ */
+static int tb_maximum_bandwidth(struct tb *tb, struct tb_port *src_port,
+				struct tb_port *dst_port, struct tb_port *port,
+				int *max_up, int *max_down, bool include_asym)
+{
+	bool downstream = tb_port_path_direction_downstream(src_port, dst_port);
+	int link_speed, link_width, up_bw, down_bw;
+
+	/*
+	 * Can include asymmetric, only if it is actually supported by
+	 * the lane adapter.
+	 */
+	if (!tb_asym_supported(src_port, dst_port, port))
+		include_asym = false;
+
+	if (tb_is_upstream_port(port)) {
+		link_speed = port->sw->link_speed;
+		/*
+		 * sw->link_width is from upstream perspective so we use
+		 * the opposite for downstream of the host router.
+		 */
+		if (port->sw->link_width == TB_LINK_WIDTH_ASYM_TX) {
+			up_bw = link_speed * 3 * 1000;
+			down_bw = link_speed * 1 * 1000;
+		} else if (port->sw->link_width == TB_LINK_WIDTH_ASYM_RX) {
+			up_bw = link_speed * 1 * 1000;
+			down_bw = link_speed * 3 * 1000;
+		} else if (include_asym) {
 			/*
-			 * sw->link_width is from upstream perspective
-			 * so we use the opposite for downstream of the
-			 * host router.
+			 * The link is symmetric at the moment but we
+			 * can switch it to asymmetric as needed. Report
+			 * this bandwidth as available (even though it
+			 * is not yet enabled).
 			 */
-			if (port->sw->link_width == TB_LINK_WIDTH_ASYM_TX) {
-				up_bw = link_speed * 3 * 1000;
-				down_bw = link_speed * 1 * 1000;
-			} else if (port->sw->link_width == TB_LINK_WIDTH_ASYM_RX) {
+			if (downstream) {
 				up_bw = link_speed * 1 * 1000;
 				down_bw = link_speed * 3 * 1000;
 			} else {
-				up_bw = link_speed * port->sw->link_width * 1000;
-				down_bw = up_bw;
+				up_bw = link_speed * 3 * 1000;
+				down_bw = link_speed * 1 * 1000;
 			}
 		} else {
-			link_speed = tb_port_get_link_speed(port);
-			if (link_speed < 0)
-				return link_speed;
-
-			link_width = tb_port_get_link_width(port);
-			if (link_width < 0)
-				return link_width;
-
-			if (link_width == TB_LINK_WIDTH_ASYM_TX) {
+			up_bw = link_speed * port->sw->link_width * 1000;
+			down_bw = up_bw;
+		}
+	} else {
+		link_speed = tb_port_get_link_speed(port);
+		if (link_speed < 0)
+			return link_speed;
+
+		link_width = tb_port_get_link_width(port);
+		if (link_width < 0)
+			return link_width;
+
+		if (link_width == TB_LINK_WIDTH_ASYM_TX) {
+			up_bw = link_speed * 1 * 1000;
+			down_bw = link_speed * 3 * 1000;
+		} else if (link_width == TB_LINK_WIDTH_ASYM_RX) {
+			up_bw = link_speed * 3 * 1000;
+			down_bw = link_speed * 1 * 1000;
+		} else if (include_asym) {
+			/*
+			 * The link is symmetric at the moment but we
+			 * can switch it to asymmetric as needed. Report
+			 * this bandwidth as available (even though it
+			 * is not yet enabled).
+			 */
+			if (downstream) {
 				up_bw = link_speed * 1 * 1000;
 				down_bw = link_speed * 3 * 1000;
-			} else if (link_width == TB_LINK_WIDTH_ASYM_RX) {
+			} else {
 				up_bw = link_speed * 3 * 1000;
 				down_bw = link_speed * 1 * 1000;
-			} else {
-				up_bw = link_speed * link_width * 1000;
-				down_bw = up_bw;
 			}
+		} else {
+			up_bw = link_speed * link_width * 1000;
+			down_bw = up_bw;
 		}
+	}
 
-		/* Leave 10% guard band */
-		up_bw -= up_bw / 10;
-		down_bw -= down_bw / 10;
-
-		tb_port_dbg(port, "link total bandwidth %d/%d Mb/s\n", up_bw,
-			    down_bw);
+	/* Leave 10% guard band */
+	*max_up = up_bw - up_bw / 10;
+	*max_down = down_bw - down_bw / 10;
 
-		/*
-		 * Find all DP tunnels that cross the port and reduce
-		 * their consumed bandwidth from the available.
-		 */
-		list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
-			int dp_consumed_up, dp_consumed_down;
+	tb_port_dbg(port, "link maximum bandwidth %d/%d Mb/s\n", *max_up, *max_down);
+	return 0;
+}
 
-			if (tb_tunnel_is_invalid(tunnel))
-				continue;
+/**
+ * tb_available_bandwidth() - Available bandwidth for tunneling
+ * @tb: Domain structure
+ * @src_port: Source protocol adapter
+ * @dst_port: Destination protocol adapter
+ * @available_up: Available bandwidth upstream (Mb/s)
+ * @available_down: Available bandwidth downstream (Mb/s)
+ * @include_asym: Include bandwidth if the link is switched from
+ *		  symmetric to asymmetric
+ *
+ * Calculates maximum available bandwidth for protocol tunneling between
+ * @src_port and @dst_port at the moment. This is minimum of maximum
+ * link bandwidth across all links reduced by currently consumed
+ * bandwidth on that link.
+ *
+ * If @include_asym is true then includes also bandwidth that can be
+ * added when the links are transitioned into asymmetric (but does not
+ * transition the links).
+ */
+static int tb_available_bandwidth(struct tb *tb, struct tb_port *src_port,
+				 struct tb_port *dst_port, int *available_up,
+				 int *available_down, bool include_asym)
+{
+	struct tb_port *port;
+	int ret;
 
-			if (!tb_tunnel_is_dp(tunnel))
-				continue;
+	/* Maximum possible bandwidth asymmetric Gen 4 link is 120 Gb/s */
+	*available_up = *available_down = 120000;
 
-			if (!tb_tunnel_port_on_path(tunnel, port))
-				continue;
+	/* Find the minimum available bandwidth over all links */
+	tb_for_each_port_on_path(src_port, dst_port, port) {
+		int max_up, max_down, consumed_up, consumed_down;
 
-			/*
-			 * Ignore the DP tunnel between src_port and
-			 * dst_port because it is the same tunnel and we
-			 * may be re-calculating estimated bandwidth.
-			 */
-			if (tunnel->src_port == src_port &&
-			    tunnel->dst_port == dst_port)
-				continue;
+		if (!tb_port_is_null(port))
+			continue;
 
-			ret = tb_tunnel_consumed_bandwidth(tunnel,
-							   &dp_consumed_up,
-							   &dp_consumed_down);
-			if (ret)
-				return ret;
+		ret = tb_maximum_bandwidth(tb, src_port, dst_port, port,
+					   &max_up, &max_down, include_asym);
+		if (ret)
+			return ret;
 
-			up_bw -= dp_consumed_up;
-			down_bw -= dp_consumed_down;
-		}
+		ret = tb_consumed_usb3_pcie_bandwidth(tb, src_port, dst_port,
+						      port, &consumed_up,
+						      &consumed_down);
+		if (ret)
+			return ret;
+		max_up -= consumed_up;
+		max_down -= consumed_down;
 
-		/*
-		 * If USB3 is tunneled from the host router down to the
-		 * branch leading to port we need to take USB3 consumed
-		 * bandwidth into account regardless whether it actually
-		 * crosses the port.
-		 */
-		up_bw -= usb3_consumed_up;
-		down_bw -= usb3_consumed_down;
+		ret = tb_consumed_dp_bandwidth(tb, src_port, dst_port, port,
+					       &consumed_up, &consumed_down);
+		if (ret)
+			return ret;
+		max_up -= consumed_up;
+		max_down -= consumed_down;
 
-		if (up_bw < *available_up)
-			*available_up = up_bw;
-		if (down_bw < *available_down)
-			*available_down = down_bw;
+		if (max_up < *available_up)
+			*available_up = max_up;
+		if (max_down < *available_down)
+			*available_down = max_down;
 	}
 
 	if (*available_up < 0)
@@ -729,21 +941,21 @@ static void tb_reclaim_usb3_bandwidth(struct tb *tb, struct tb_port *src_port,
 	if (!tunnel)
 		return;
 
-	tb_dbg(tb, "reclaiming unused bandwidth for USB3\n");
+	tb_tunnel_dbg(tunnel, "reclaiming unused bandwidth\n");
 
 	/*
 	 * Calculate available bandwidth for the first hop USB3 tunnel.
 	 * That determines the whole USB3 bandwidth for this branch.
 	 */
 	ret = tb_available_bandwidth(tb, tunnel->src_port, tunnel->dst_port,
-				     &available_up, &available_down);
+				     &available_up, &available_down, false);
 	if (ret) {
-		tb_warn(tb, "failed to calculate available bandwidth\n");
+		tb_tunnel_warn(tunnel, "failed to calculate available bandwidth\n");
 		return;
 	}
 
-	tb_dbg(tb, "available bandwidth for USB3 %d/%d Mb/s\n",
-	       available_up, available_down);
+	tb_tunnel_dbg(tunnel, "available bandwidth %d/%d Mb/s\n", available_up,
+		      available_down);
 
 	tb_tunnel_reclaim_available_bandwidth(tunnel, &available_up, &available_down);
 }
@@ -794,8 +1006,8 @@ static int tb_tunnel_usb3(struct tb *tb, struct tb_switch *sw)
 			return ret;
 	}
 
-	ret = tb_available_bandwidth(tb, down, up, &available_up,
-				     &available_down);
+	ret = tb_available_bandwidth(tb, down, up, &available_up, &available_down,
+				     false);
 	if (ret)
 		goto err_reclaim;
 
@@ -856,6 +1068,225 @@ static int tb_create_usb3_tunnels(struct tb_switch *sw)
 	return 0;
 }
 
+/**
+ * tb_configure_asym() - Transition links to asymmetric if needed
+ * @tb: Domain structure
+ * @src_port: Source adapter to start the transition
+ * @dst_port: Destination adapter
+ * @requested_up: Additional bandwidth (Mb/s) required upstream
+ * @requested_down: Additional bandwidth (Mb/s) required downstream
+ *
+ * Transition links between @src_port and @dst_port into asymmetric, with
+ * three lanes in the direction from @src_port towards @dst_port and one lane
+ * in the opposite direction, if the bandwidth requirements
+ * (requested + currently consumed) on that link exceed @asym_threshold.
+ *
+ * Must be called with available >= requested over all links.
+ */
+static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
+			     struct tb_port *dst_port, int requested_up,
+			     int requested_down)
+{
+	struct tb_switch *sw;
+	bool clx, downstream;
+	struct tb_port *up;
+	int ret = 0;
+
+	if (!asym_threshold)
+		return 0;
+
+	/* Disable CL states before doing any transitions */
+	downstream = tb_port_path_direction_downstream(src_port, dst_port);
+	/* Pick up router deepest in the hierarchy */
+	if (downstream)
+		sw = dst_port->sw;
+	else
+		sw = src_port->sw;
+
+	clx = tb_disable_clx(sw);
+
+	tb_for_each_upstream_port_on_path(src_port, dst_port, up) {
+		int consumed_up, consumed_down;
+		enum tb_link_width width;
+
+		ret = tb_consumed_dp_bandwidth(tb, src_port, dst_port, up,
+					       &consumed_up, &consumed_down);
+		if (ret)
+			break;
+
+		if (downstream) {
+			/*
+			 * Downstream so make sure upstream is within the 36G
+			 * (40G - guard band 10%), and the requested is above
+			 * what the threshold is.
+			 */
+			if (consumed_up + requested_up >= TB_ASYM_MIN) {
+				ret = -ENOBUFS;
+				break;
+			}
+			/* Does consumed + requested exceed the threshold */
+			if (consumed_down + requested_down < asym_threshold)
+				continue;
+
+			width = TB_LINK_WIDTH_ASYM_RX;
+		} else {
+			/* Upstream, the opposite of above */
+			if (consumed_down + requested_down >= TB_ASYM_MIN) {
+				ret = -ENOBUFS;
+				break;
+			}
+			if (consumed_up + requested_up < asym_threshold)
+				continue;
+
+			width = TB_LINK_WIDTH_ASYM_TX;
+		}
+
+		if (up->sw->link_width == width)
+			continue;
+
+		if (!tb_port_width_supported(up, width))
+			continue;
+
+		tb_sw_dbg(up->sw, "configuring asymmetric link\n");
+
+		/*
+		 * Here requested + consumed > threshold so we need to
+		 * transtion the link into asymmetric now.
+		 */
+		ret = tb_switch_set_link_width(up->sw, width);
+		if (ret) {
+			tb_sw_warn(up->sw, "failed to set link width\n");
+			break;
+		}
+	}
+
+	/* Re-enable CL states if they were previosly enabled */
+	if (clx)
+		tb_enable_clx(sw);
+
+	return ret;
+}
+
+/**
+ * tb_configure_sym() - Transition links to symmetric if possible
+ * @tb: Domain structure
+ * @src_port: Source adapter to start the transition
+ * @dst_port: Destination adapter
+ * @requested_up: New lower bandwidth request upstream (Mb/s)
+ * @requested_down: New lower bandwidth request downstream (Mb/s)
+ *
+ * Goes over each link from @src_port to @dst_port and tries to
+ * transition the link to symmetric if the currently consumed bandwidth
+ * allows.
+ */
+static int tb_configure_sym(struct tb *tb, struct tb_port *src_port,
+			    struct tb_port *dst_port, int requested_up,
+			    int requested_down)
+{
+	struct tb_switch *sw;
+	bool clx, downstream;
+	struct tb_port *up;
+	int ret = 0;
+
+	if (!asym_threshold)
+		return 0;
+
+	/* Disable CL states before doing any transitions */
+	downstream = tb_port_path_direction_downstream(src_port, dst_port);
+	/* Pick up router deepest in the hierarchy */
+	if (downstream)
+		sw = dst_port->sw;
+	else
+		sw = src_port->sw;
+
+	clx = tb_disable_clx(sw);
+
+	tb_for_each_upstream_port_on_path(src_port, dst_port, up) {
+		int consumed_up, consumed_down;
+
+		/* Already symmetric */
+		if (up->sw->link_width <= TB_LINK_WIDTH_DUAL)
+			continue;
+		/* Unplugged, no need to switch */
+		if (up->sw->is_unplugged)
+			continue;
+
+		ret = tb_consumed_dp_bandwidth(tb, src_port, dst_port, up,
+					       &consumed_up, &consumed_down);
+		if (ret)
+			break;
+
+		if (downstream) {
+			/*
+			 * Downstream so we want the consumed_down < threshold.
+			 * Upstream traffic should be less than 36G (40G
+			 * guard band 10%) as the link was configured asymmetric
+			 * already.
+			 */
+			if (consumed_down + requested_down >= asym_threshold)
+				continue;
+		} else {
+			if (consumed_up + requested_up >= asym_threshold)
+				continue;
+		}
+
+		if (up->sw->link_width == TB_LINK_WIDTH_DUAL)
+			continue;
+
+		tb_sw_dbg(up->sw, "configuring symmetric link\n");
+
+		ret = tb_switch_set_link_width(up->sw, TB_LINK_WIDTH_DUAL);
+		if (ret) {
+			tb_sw_warn(up->sw, "failed to set link width\n");
+			break;
+		}
+	}
+
+	/* Re-enable CL states if they were previosly enabled */
+	if (clx)
+		tb_enable_clx(sw);
+
+	return ret;
+}
+
+static void tb_configure_link(struct tb_port *down, struct tb_port *up,
+			      struct tb_switch *sw)
+{
+	struct tb *tb = sw->tb;
+
+	/* Link the routers using both links if available */
+	down->remote = up;
+	up->remote = down;
+	if (down->dual_link_port && up->dual_link_port) {
+		down->dual_link_port->remote = up->dual_link_port;
+		up->dual_link_port->remote = down->dual_link_port;
+	}
+
+	/*
+	 * Enable lane bonding if the link is currently two single lane
+	 * links.
+	 */
+	if (sw->link_width < TB_LINK_WIDTH_DUAL)
+		tb_switch_set_link_width(sw, TB_LINK_WIDTH_DUAL);
+
+	/*
+	 * Device router that comes up as symmetric link is
+	 * connected deeper in the hierarchy, we transition the links
+	 * above into symmetric if bandwidth allows.
+	 */
+	if (tb_switch_depth(sw) > 1 &&
+	    tb_port_get_link_generation(up) >= 4 &&
+	    up->sw->link_width == TB_LINK_WIDTH_DUAL) {
+		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);
+	}
+
+	/* Set the link configured */
+	tb_switch_configure_link(sw);
+}
+
 static void tb_scan_port(struct tb_port *port);
 
 /*
@@ -964,19 +1395,9 @@ static void tb_scan_port(struct tb_port *port)
 		goto out_rpm_put;
 	}
 
-	/* Link the switches using both links if available */
 	upstream_port = tb_upstream_port(sw);
-	port->remote = upstream_port;
-	upstream_port->remote = port;
-	if (port->dual_link_port && upstream_port->dual_link_port) {
-		port->dual_link_port->remote = upstream_port->dual_link_port;
-		upstream_port->dual_link_port->remote = port->dual_link_port;
-	}
+	tb_configure_link(port, upstream_port, sw);
 
-	/* Enable lane bonding if supported */
-	tb_switch_lane_bonding_enable(sw);
-	/* Set the link configured */
-	tb_switch_configure_link(sw);
 	/*
 	 * CL0s and CL1 are enabled and supported together.
 	 * Silently ignore CLx enabling in case CLx is not supported.
@@ -1040,6 +1461,11 @@ static void tb_deactivate_and_free_tunnel(struct tb_tunnel *tunnel)
 		 * deallocated properly.
 		 */
 		tb_switch_dealloc_dp_resource(src_port->sw, src_port);
+		/*
+		 * If bandwidth on a link is < asym_threshold
+		 * transition the link to symmetric.
+		 */
+		tb_configure_sym(tb, src_port, dst_port, 0, 0);
 		/* 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);
@@ -1092,7 +1518,8 @@ static void tb_free_unplugged_children(struct tb_switch *sw)
 			tb_retimer_remove_all(port);
 			tb_remove_dp_resources(port->remote->sw);
 			tb_switch_unconfigure_link(port->remote->sw);
-			tb_switch_lane_bonding_disable(port->remote->sw);
+			tb_switch_set_link_width(port->remote->sw,
+						 TB_LINK_WIDTH_SINGLE);
 			tb_switch_remove(port->remote->sw);
 			port->remote = NULL;
 			if (port->dual_link_port)
@@ -1188,7 +1615,7 @@ tb_recalc_estimated_bandwidth_for_group(struct tb_bandwidth_group *group)
 			ret = tb_release_unused_usb3_bandwidth(tb,
 				first_tunnel->src_port, first_tunnel->dst_port);
 			if (ret) {
-				tb_port_warn(in,
+				tb_tunnel_warn(tunnel,
 					"failed to release unused bandwidth\n");
 				break;
 			}
@@ -1196,9 +1623,9 @@ tb_recalc_estimated_bandwidth_for_group(struct tb_bandwidth_group *group)
 
 		out = tunnel->dst_port;
 		ret = tb_available_bandwidth(tb, in, out, &estimated_up,
-					     &estimated_down);
+					     &estimated_down, true);
 		if (ret) {
-			tb_port_warn(in,
+			tb_tunnel_warn(tunnel,
 				"failed to re-calculate estimated bandwidth\n");
 			break;
 		}
@@ -1209,16 +1636,18 @@ tb_recalc_estimated_bandwidth_for_group(struct tb_bandwidth_group *group)
 		 *  - available bandwidth along the path
 		 *  - bandwidth allocated for USB 3.x but not used.
 		 */
-		tb_port_dbg(in, "re-calculated estimated bandwidth %u/%u Mb/s\n",
-			    estimated_up, estimated_down);
+		tb_tunnel_dbg(tunnel,
+			      "re-calculated estimated bandwidth %u/%u Mb/s\n",
+			      estimated_up, estimated_down);
 
-		if (in->sw->config.depth < out->sw->config.depth)
+		if (tb_port_path_direction_downstream(in, out))
 			estimated_bw = estimated_down;
 		else
 			estimated_bw = estimated_up;
 
 		if (usb4_dp_port_set_estimated_bandwidth(in, estimated_bw))
-			tb_port_warn(in, "failed to update estimated bandwidth\n");
+			tb_tunnel_warn(tunnel,
+				       "failed to update estimated bandwidth\n");
 	}
 
 	if (first_tunnel)
@@ -1282,18 +1711,14 @@ static struct tb_port *tb_find_dp_out(struct tb *tb, struct tb_port *in)
 	return NULL;
 }
 
-static void tb_tunnel_dp(struct tb *tb)
+static bool tb_tunnel_one_dp(struct tb *tb)
 {
 	int available_up, available_down, ret, link_nr;
 	struct tb_cm *tcm = tb_priv(tb);
 	struct tb_port *port, *in, *out;
+	int consumed_up, consumed_down;
 	struct tb_tunnel *tunnel;
 
-	if (!tb_acpi_may_tunnel_dp()) {
-		tb_dbg(tb, "DP tunneling disabled, not creating tunnel\n");
-		return;
-	}
-
 	/*
 	 * Find pair of inactive DP IN and DP OUT adapters and then
 	 * establish a DP tunnel between them.
@@ -1311,22 +1736,21 @@ static void tb_tunnel_dp(struct tb *tb)
 			continue;
 		}
 
-		tb_port_dbg(port, "DP IN available\n");
+		in = port;
+		tb_port_dbg(in, "DP IN available\n");
 
 		out = tb_find_dp_out(tb, port);
-		if (out) {
-			in = port;
+		if (out)
 			break;
-		}
 	}
 
 	if (!in) {
 		tb_dbg(tb, "no suitable DP IN adapter available, not tunneling\n");
-		return;
+		return false;
 	}
 	if (!out) {
 		tb_dbg(tb, "no suitable DP OUT adapter available, not tunneling\n");
-		return;
+		return false;
 	}
 
 	/*
@@ -1369,7 +1793,8 @@ static void tb_tunnel_dp(struct tb *tb)
 		goto err_detach_group;
 	}
 
-	ret = tb_available_bandwidth(tb, in, out, &available_up, &available_down);
+	ret = tb_available_bandwidth(tb, in, out, &available_up, &available_down,
+				     true);
 	if (ret)
 		goto err_reclaim_usb;
 
@@ -1391,6 +1816,13 @@ static void tb_tunnel_dp(struct tb *tb)
 	list_add_tail(&tunnel->list, &tcm->tunnel_list);
 	tb_reclaim_usb3_bandwidth(tb, in, out);
 
+	/*
+	 * Transition the links to asymmetric if the consumption exceeds
+	 * the threshold.
+	 */
+	if (!tb_tunnel_consumed_bandwidth(tunnel, &consumed_up, &consumed_down))
+		tb_configure_asym(tb, in, out, consumed_up, consumed_down);
+
 	/* Update the domain with the new bandwidth estimation */
 	tb_recalc_estimated_bandwidth(tb);
 
@@ -1399,7 +1831,7 @@ static void tb_tunnel_dp(struct tb *tb)
 	 * TMU mode to HiFi for CL0s to work.
 	 */
 	tb_increase_tmu_accuracy(tunnel);
-	return;
+	return true;
 
 err_free:
 	tb_tunnel_free(tunnel);
@@ -1414,6 +1846,19 @@ err_rpm_put:
 	pm_runtime_put_autosuspend(&out->sw->dev);
 	pm_runtime_mark_last_busy(&in->sw->dev);
 	pm_runtime_put_autosuspend(&in->sw->dev);
+
+	return false;
+}
+
+static void tb_tunnel_dp(struct tb *tb)
+{
+	if (!tb_acpi_may_tunnel_dp()) {
+		tb_dbg(tb, "DP tunneling disabled, not creating tunnel\n");
+		return;
+	}
+
+	while (tb_tunnel_one_dp(tb))
+		;
 }
 
 static void tb_dp_resource_unavailable(struct tb *tb, struct tb_port *port)
@@ -1701,7 +2146,8 @@ static void tb_handle_hotplug(struct work_struct *work)
 			tb_remove_dp_resources(port->remote->sw);
 			tb_switch_tmu_disable(port->remote->sw);
 			tb_switch_unconfigure_link(port->remote->sw);
-			tb_switch_lane_bonding_disable(port->remote->sw);
+			tb_switch_set_link_width(port->remote->sw,
+						 TB_LINK_WIDTH_SINGLE);
 			tb_switch_remove(port->remote->sw);
 			port->remote = NULL;
 			if (port->dual_link_port)
@@ -1781,8 +2227,8 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 	in = tunnel->src_port;
 	out = tunnel->dst_port;
 
-	tb_port_dbg(in, "bandwidth allocated currently %d/%d Mb/s\n",
-		    allocated_up, allocated_down);
+	tb_tunnel_dbg(tunnel, "bandwidth allocated currently %d/%d Mb/s\n",
+		      allocated_up, allocated_down);
 
 	/*
 	 * If we get rounded up request from graphics side, say HBR2 x 4
@@ -1823,20 +2269,26 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 	else if (requested_down_corrected < 0)
 		requested_down_corrected = 0;
 
-	tb_port_dbg(in, "corrected bandwidth request %d/%d Mb/s\n",
-		    requested_up_corrected, requested_down_corrected);
+	tb_tunnel_dbg(tunnel, "corrected bandwidth request %d/%d Mb/s\n",
+		      requested_up_corrected, requested_down_corrected);
 
 	if ((*requested_up >= 0 && requested_up_corrected > max_up_rounded) ||
 	    (*requested_down >= 0 && requested_down_corrected > max_down_rounded)) {
-		tb_port_dbg(in, "bandwidth request too high (%d/%d Mb/s > %d/%d Mb/s)\n",
-			    requested_up_corrected, requested_down_corrected,
-			    max_up_rounded, max_down_rounded);
+		tb_tunnel_dbg(tunnel,
+			      "bandwidth request too high (%d/%d Mb/s > %d/%d Mb/s)\n",
+			      requested_up_corrected, requested_down_corrected,
+			      max_up_rounded, max_down_rounded);
 		return -ENOBUFS;
 	}
 
 	if ((*requested_up >= 0 && requested_up_corrected <= allocated_up) ||
 	    (*requested_down >= 0 && requested_down_corrected <= allocated_down)) {
 		/*
+		 * If bandwidth on a link is < asym_threshold transition
+		 * the link to symmetric.
+		 */
+		tb_configure_sym(tb, in, out, *requested_up, *requested_down);
+		/*
 		 * If requested bandwidth is less or equal than what is
 		 * currently allocated to that tunnel we simply change
 		 * the reservation of the tunnel. Since all the tunnels
@@ -1861,17 +2313,33 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
 	 * are also in the same group but we use the same function here
 	 * that we use with the normal bandwidth allocation).
 	 */
-	ret = tb_available_bandwidth(tb, in, out, &available_up, &available_down);
+	ret = tb_available_bandwidth(tb, in, out, &available_up, &available_down,
+				     true);
 	if (ret)
 		goto reclaim;
 
-	tb_port_dbg(in, "bandwidth available for allocation %d/%d Mb/s\n",
-		    available_up, available_down);
+	tb_tunnel_dbg(tunnel, "bandwidth available for allocation %d/%d Mb/s\n",
+		      available_up, available_down);
 
 	if ((*requested_up >= 0 && available_up >= requested_up_corrected) ||
 	    (*requested_down >= 0 && available_down >= requested_down_corrected)) {
+		/*
+		 * If bandwidth on a link is >= asym_threshold
+		 * transition the link to asymmetric.
+		 */
+		ret = tb_configure_asym(tb, in, out, *requested_up,
+					*requested_down);
+		if (ret) {
+			tb_configure_sym(tb, in, out, 0, 0);
+			return ret;
+		}
+
 		ret = tb_tunnel_alloc_bandwidth(tunnel, requested_up,
 						requested_down);
+		if (ret) {
+			tb_tunnel_warn(tunnel, "failed to allocate bandwidth\n");
+			tb_configure_sym(tb, in, out, 0, 0);
+		}
 	} else {
 		ret = -ENOBUFS;
 	}
@@ -1937,7 +2405,7 @@ static void tb_handle_dp_bandwidth_request(struct work_struct *work)
 
 	out = tunnel->dst_port;
 
-	if (in->sw->config.depth < out->sw->config.depth) {
+	if (tb_port_path_direction_downstream(in, out)) {
 		requested_up = -1;
 		requested_down = requested_bw;
 	} else {
@@ -1948,12 +2416,15 @@ static void tb_handle_dp_bandwidth_request(struct work_struct *work)
 	ret = tb_alloc_dp_bandwidth(tunnel, &requested_up, &requested_down);
 	if (ret) {
 		if (ret == -ENOBUFS)
-			tb_port_warn(in, "not enough bandwidth available\n");
+			tb_tunnel_warn(tunnel,
+				       "not enough bandwidth available\n");
 		else
-			tb_port_warn(in, "failed to change bandwidth allocation\n");
+			tb_tunnel_warn(tunnel,
+				       "failed to change bandwidth allocation\n");
 	} else {
-		tb_port_dbg(in, "bandwidth allocation changed to %d/%d Mb/s\n",
-			    requested_up, requested_down);
+		tb_tunnel_dbg(tunnel,
+			      "bandwidth allocation changed to %d/%d Mb/s\n",
+			      requested_up, requested_down);
 
 		/* Update other clients about the allocation change */
 		tb_recalc_estimated_bandwidth(tb);
@@ -2181,7 +2652,8 @@ static void tb_restore_children(struct tb_switch *sw)
 			continue;
 
 		if (port->remote) {
-			tb_switch_lane_bonding_enable(port->remote->sw);
+			tb_switch_set_link_width(port->remote->sw,
+						 port->remote->sw->link_width);
 			tb_switch_configure_link(port->remote->sw);
 
 			tb_restore_children(port->remote->sw);