Commit 9d2d0a5c authored by Mika Westerberg's avatar Mika Westerberg
Browse files

thunderbolt: Use different lane for second DisplayPort tunnel 



Brad reported that on Apple hardware with Light Ridge or Falcon Ridge
controller, plugging in a chain of Thunderbolt displays (Light Ridge
based controllers) causes all kinds of tearing and flickering. The
reason for this is that on Thunderbolt 1 hardware there is no lane
bonding so we have two independent 10 Gb/s lanes, and currently Linux
tunnels both displays through the lane 1. This makes the displays to
share the 10 Gb/s bandwidth which may not be enough for higher
resolutions.

For this reason make the second tunnel go through the lane 0 instead.
This seems to match what the macOS connection manager is also doing.

Reported-by: default avatarBrad Campbell <lists2009@fnarfbargle.com>
Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: default avatarBrad Campbell <lists2009@fnarfbargle.com>
parent 259e0c71

drivers/thunderbolt/tb.c

+17 −2
Original line number Diff line number Diff line
@@ -867,7 +867,7 @@ static struct tb_port *tb_find_dp_out(struct tb *tb, struct tb_port *in) 


static void tb_tunnel_dp(struct tb *tb)

{

	int available_up, available_down, ret;

	int available_up, available_down, ret, link_nr;

	struct tb_cm *tcm = tb_priv(tb);

	struct tb_port *port, *in, *out;

	struct tb_tunnel *tunnel;
@@ -912,6 +912,20 @@ static void tb_tunnel_dp(struct tb *tb) 
		return;

	}



	/*

	 * This is only applicable to links that are not bonded (so

	 * when Thunderbolt 1 hardware is involved somewhere in the

	 * topology). For these try to share the DP bandwidth between

	 * the two lanes.

	 */

	link_nr = 1;

	list_for_each_entry(tunnel, &tcm->tunnel_list, list) {

		if (tb_tunnel_is_dp(tunnel)) {

			link_nr = 0;

			break;

		}

	}



	/*

	 * DP stream needs the domain to be active so runtime resume

	 * both ends of the tunnel.
@@ -943,7 +957,8 @@ static void tb_tunnel_dp(struct tb *tb) 
	tb_dbg(tb, "available bandwidth for new DP tunnel %u/%u Mb/s\n",

	       available_up, available_down);



	tunnel = tb_tunnel_alloc_dp(tb, in, out, available_up, available_down);

	tunnel = tb_tunnel_alloc_dp(tb, in, out, link_nr, available_up,

				    available_down);

	if (!tunnel) {

		tb_port_dbg(out, "could not allocate DP tunnel\n");

		goto err_reclaim;

drivers/thunderbolt/test.c

+8 −8
Original line number Diff line number Diff line
@@ -1348,7 +1348,7 @@ static void tb_test_tunnel_dp(struct kunit *test) 
	in = &host->ports[5];

	out = &dev->ports[13];



	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, tunnel != NULL);

	KUNIT_EXPECT_EQ(test, tunnel->type, TB_TUNNEL_DP);

	KUNIT_EXPECT_PTR_EQ(test, tunnel->src_port, in);
@@ -1394,7 +1394,7 @@ static void tb_test_tunnel_dp_chain(struct kunit *test) 
	in = &host->ports[5];

	out = &dev4->ports[14];



	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, tunnel != NULL);

	KUNIT_EXPECT_EQ(test, tunnel->type, TB_TUNNEL_DP);

	KUNIT_EXPECT_PTR_EQ(test, tunnel->src_port, in);
@@ -1444,7 +1444,7 @@ static void tb_test_tunnel_dp_tree(struct kunit *test) 
	in = &dev2->ports[13];

	out = &dev5->ports[13];



	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, tunnel != NULL);

	KUNIT_EXPECT_EQ(test, tunnel->type, TB_TUNNEL_DP);

	KUNIT_EXPECT_PTR_EQ(test, tunnel->src_port, in);
@@ -1509,7 +1509,7 @@ static void tb_test_tunnel_dp_max_length(struct kunit *test) 
	in = &dev6->ports[13];

	out = &dev12->ports[13];



	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, tunnel != NULL);

	KUNIT_EXPECT_EQ(test, tunnel->type, TB_TUNNEL_DP);

	KUNIT_EXPECT_PTR_EQ(test, tunnel->src_port, in);
@@ -1627,7 +1627,7 @@ static void tb_test_tunnel_port_on_path(struct kunit *test) 
	in = &dev2->ports[13];

	out = &dev5->ports[13];



	dp_tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	dp_tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, dp_tunnel != NULL);



	KUNIT_EXPECT_TRUE(test, tb_tunnel_port_on_path(dp_tunnel, in));
@@ -2009,7 +2009,7 @@ static void tb_test_credit_alloc_dp(struct kunit *test) 
	in = &host->ports[5];

	out = &dev->ports[14];



	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	tunnel = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, tunnel != NULL);

	KUNIT_ASSERT_EQ(test, tunnel->npaths, (size_t)3);
@@ -2245,7 +2245,7 @@ static struct tb_tunnel *TB_TEST_DP_TUNNEL1(struct kunit *test, 


	in = &host->ports[5];

	out = &dev->ports[13];

	dp_tunnel1 = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	dp_tunnel1 = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, dp_tunnel1 != NULL);

	KUNIT_ASSERT_EQ(test, dp_tunnel1->npaths, (size_t)3);
@@ -2282,7 +2282,7 @@ static struct tb_tunnel *TB_TEST_DP_TUNNEL2(struct kunit *test, 


	in = &host->ports[6];

	out = &dev->ports[14];

	dp_tunnel2 = tb_tunnel_alloc_dp(NULL, in, out, 0, 0);

	dp_tunnel2 = tb_tunnel_alloc_dp(NULL, in, out, 1, 0, 0);

	KUNIT_ASSERT_TRUE(test, dp_tunnel2 != NULL);

	KUNIT_ASSERT_EQ(test, dp_tunnel2->npaths, (size_t)3);

drivers/thunderbolt/tunnel.c

+6 −5
Original line number Diff line number Diff line
@@ -858,6 +858,7 @@ struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in, 
 * @tb: Pointer to the domain structure

 * @in: DP in adapter port

 * @out: DP out adapter port

 * @link_nr: Preferred lane adapter when the link is not bonded

 * @max_up: Maximum available upstream bandwidth for the DP tunnel (%0

 *	    if not limited)

 * @max_down: Maximum available downstream bandwidth for the DP tunnel
@@ -869,8 +870,8 @@ struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in, 
 * Return: Returns a tb_tunnel on success or NULL on failure.

 */

struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,

				     struct tb_port *out, int max_up,

				     int max_down)

				     struct tb_port *out, int link_nr,

				     int max_up, int max_down)

{

	struct tb_tunnel *tunnel;

	struct tb_path **paths;
@@ -894,21 +895,21 @@ struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in, 
	paths = tunnel->paths;



	path = tb_path_alloc(tb, in, TB_DP_VIDEO_HOPID, out, TB_DP_VIDEO_HOPID,

			     1, "Video");

			     link_nr, "Video");

	if (!path)

		goto err_free;

	tb_dp_init_video_path(path);

	paths[TB_DP_VIDEO_PATH_OUT] = path;



	path = tb_path_alloc(tb, in, TB_DP_AUX_TX_HOPID, out,

			     TB_DP_AUX_TX_HOPID, 1, "AUX TX");

			     TB_DP_AUX_TX_HOPID, link_nr, "AUX TX");

	if (!path)

		goto err_free;

	tb_dp_init_aux_path(path);

	paths[TB_DP_AUX_PATH_OUT] = path;



	path = tb_path_alloc(tb, out, TB_DP_AUX_RX_HOPID, in,

			     TB_DP_AUX_RX_HOPID, 1, "AUX RX");

			     TB_DP_AUX_RX_HOPID, link_nr, "AUX RX");

	if (!path)

		goto err_free;

	tb_dp_init_aux_path(path);

drivers/thunderbolt/tunnel.h

+2 −2
Original line number Diff line number Diff line
@@ -71,8 +71,8 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up, 
struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in,

					bool alloc_hopid);

struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,

				     struct tb_port *out, int max_up,

				     int max_down);

				     struct tb_port *out, int link_nr,

				     int max_up, int max_down);

struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,

				      struct tb_port *dst, int transmit_path,

				      int transmit_ring, int receive_path,