Merge branch 'thunderbolt-end-to-end-flow-control'

Mika Westerberg says:

====================
thunderbolt: net: Enable full end-to-end flow control

Thunderbolt/USB4 host controllers support full end-to-end flow control
that prevents dropping packets if there are not enough hardware receive
buffers. So far it has not been enabled for the networking driver yet
but this series changes that. There is one snag though: the second
generation (Intel Falcon Ridge) had a bug that needs special quirk to
get it working. We had that in the early stages of the Thunderbolt/USB4
driver but it got dropped because it was not needed at the time. Now we
add it back as a quirk for the host controller (NHI).

The first patch of this series is a bugfix that I'm planning to push for
v6.0-rc. Rest are v6.1 material. This also includes a patch that shows
the XDomain link type in sysfs the same way we do for USB4 routers and
updates the networking driver module description.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 40 insertions, 22 deletions

diff --git a/drivers/net/thunderbolt.c b/drivers/net/thunderbolt.c
index ff5d0e98a088..c058eabd7b36 100644
--- a/drivers/net/thunderbolt.c
+++ b/drivers/net/thunderbolt.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Networking over Thunderbolt cable using Apple ThunderboltIP protocol
+ * Networking over Thunderbolt/USB4 cables using USB4NET protocol
+ * (formerly Apple ThunderboltIP).
  *
  * Copyright (C) 2017, Intel Corporation
  * Authors: Amir Levy <amir.jer.levy@intel.com>
@@ -30,6 +31,7 @@
 #define TBNET_RING_SIZE		256
 #define TBNET_LOGIN_RETRIES	60
 #define TBNET_LOGOUT_RETRIES	10
+#define TBNET_E2E		BIT(0)
 #define TBNET_MATCH_FRAGS_ID	BIT(1)
 #define TBNET_64K_FRAMES	BIT(2)
 #define TBNET_MAX_MTU		SZ_64K
@@ -209,6 +211,10 @@ static const uuid_t tbnet_svc_uuid =
 
 static struct tb_property_dir *tbnet_dir;
 
+static bool tbnet_e2e = true;
+module_param_named(e2e, tbnet_e2e, bool, 0444);
+MODULE_PARM_DESC(e2e, "USB4NET full end-to-end flow control (default: true)");
+
 static void tbnet_fill_header(struct thunderbolt_ip_header *hdr, u64 route,
 	u8 sequence, const uuid_t *initiator_uuid, const uuid_t *target_uuid,
 	enum thunderbolt_ip_type type, size_t size, u32 command_id)
@@ -612,18 +618,13 @@ static void tbnet_connected_work(struct work_struct *work)
 		return;
 	}
 
-	/* Both logins successful so enable the high-speed DMA paths and
-	 * start the network device queue.
+	/* Both logins successful so enable the rings, high-speed DMA
+	 * paths and start the network device queue.
+	 *
+	 * Note we enable the DMA paths last to make sure we have primed
+	 * the Rx ring before any incoming packets are allowed to
+	 * arrive.
 	 */
-	ret = tb_xdomain_enable_paths(net->xd, net->local_transmit_path,
-				      net->rx_ring.ring->hop,
-				      net->remote_transmit_path,
-				      net->tx_ring.ring->hop);
-	if (ret) {
-		netdev_err(net->dev, "failed to enable DMA paths\n");
-		return;
-	}
-
 	tb_ring_start(net->tx_ring.ring);
 	tb_ring_start(net->rx_ring.ring);
 
@@ -635,10 +636,21 @@ static void tbnet_connected_work(struct work_struct *work)
 	if (ret)
 		goto err_free_rx_buffers;
 
+	ret = tb_xdomain_enable_paths(net->xd, net->local_transmit_path,
+				      net->rx_ring.ring->hop,
+				      net->remote_transmit_path,
+				      net->tx_ring.ring->hop);
+	if (ret) {
+		netdev_err(net->dev, "failed to enable DMA paths\n");
+		goto err_free_tx_buffers;
+	}
+
 	netif_carrier_on(net->dev);
 	netif_start_queue(net->dev);
 	return;
 
+err_free_tx_buffers:
+	tbnet_free_buffers(&net->tx_ring);
 err_free_rx_buffers:
 	tbnet_free_buffers(&net->rx_ring);
 err_stop_rings:
@@ -867,6 +879,7 @@ static int tbnet_open(struct net_device *dev)
 	struct tb_xdomain *xd = net->xd;
 	u16 sof_mask, eof_mask;
 	struct tb_ring *ring;
+	unsigned int flags;
 	int hopid;
 
 	netif_carrier_off(dev);
@@ -891,9 +904,14 @@ static int tbnet_open(struct net_device *dev)
 	sof_mask = BIT(TBIP_PDF_FRAME_START);
 	eof_mask = BIT(TBIP_PDF_FRAME_END);
 
-	ring = tb_ring_alloc_rx(xd->tb->nhi, -1, TBNET_RING_SIZE,
-				RING_FLAG_FRAME, 0, sof_mask, eof_mask,
-				tbnet_start_poll, net);
+	flags = RING_FLAG_FRAME;
+	/* Only enable full E2E if the other end supports it too */
+	if (tbnet_e2e && net->svc->prtcstns & TBNET_E2E)
+		flags |= RING_FLAG_E2E;
+
+	ring = tb_ring_alloc_rx(xd->tb->nhi, -1, TBNET_RING_SIZE, flags,
+				net->tx_ring.ring->hop, sof_mask,
+				eof_mask, tbnet_start_poll, net);
 	if (!ring) {
 		netdev_err(dev, "failed to allocate Rx ring\n");
 		tb_ring_free(net->tx_ring.ring);
@@ -1356,6 +1374,7 @@ static struct tb_service_driver tbnet_driver = {
 
 static int __init tbnet_init(void)
 {
+	unsigned int flags;
 	int ret;
 
 	tbnet_dir = tb_property_create_dir(&tbnet_dir_uuid);
@@ -1365,12 +1384,11 @@ static int __init tbnet_init(void)
 	tb_property_add_immediate(tbnet_dir, "prtcid", 1);
 	tb_property_add_immediate(tbnet_dir, "prtcvers", 1);
 	tb_property_add_immediate(tbnet_dir, "prtcrevs", 1);
-	/* Currently only announce support for match frags ID (bit 1). Bit 0
-	 * is reserved for full E2E flow control which we do not support at
-	 * the moment.
-	 */
-	tb_property_add_immediate(tbnet_dir, "prtcstns",
-				  TBNET_MATCH_FRAGS_ID | TBNET_64K_FRAMES);
+
+	flags = TBNET_MATCH_FRAGS_ID | TBNET_64K_FRAMES;
+	if (tbnet_e2e)
+		flags |= TBNET_E2E;
+	tb_property_add_immediate(tbnet_dir, "prtcstns", flags);
 
 	ret = tb_register_property_dir("network", tbnet_dir);
 	if (ret) {
@@ -1393,5 +1411,5 @@ module_exit(tbnet_exit);
 MODULE_AUTHOR("Amir Levy <amir.jer.levy@intel.com>");
 MODULE_AUTHOR("Michael Jamet <michael.jamet@intel.com>");
 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
-MODULE_DESCRIPTION("Thunderbolt network driver");
+MODULE_DESCRIPTION("Thunderbolt/USB4 network driver");
 MODULE_LICENSE("GPL v2");