[PATCH] net: thunderbolt: Enable e2e flow control in two direction

From: zhangjianrong
Date: Tue Jun 24 2025 - 05:32:20 EST


According to USB4 specification, if E2E flow control is disabled for
the Transmit Descriptor Ring, the Host Interface Adapter Layer shall
not require any credits to be available before transmitting a Tunneled
Packet from this Transmit Descriptor Ring, so e2e flow control should
be enabled in two direction.

Signed-off-by: zhangjianrong <zhangjianrong5@xxxxxxxxxx>
---
drivers/net/thunderbolt/main.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/net/thunderbolt/main.c b/drivers/net/thunderbolt/main.c
index 0a53ec293d04..643cf67840b5 100644
--- a/drivers/net/thunderbolt/main.c
+++ b/drivers/net/thunderbolt/main.c
@@ -924,8 +924,12 @@ static int tbnet_open(struct net_device *dev)

netif_carrier_off(dev);

- ring = tb_ring_alloc_tx(xd->tb->nhi, -1, TBNET_RING_SIZE,
- RING_FLAG_FRAME);
+ 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_tx(xd->tb->nhi, -1, TBNET_RING_SIZE, flags);
if (!ring) {
netdev_err(dev, "failed to allocate Tx ring\n");
return -ENOMEM;
@@ -944,11 +948,6 @@ static int tbnet_open(struct net_device *dev)
sof_mask = BIT(TBIP_PDF_FRAME_START);
eof_mask = BIT(TBIP_PDF_FRAME_END);

- 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);
--
2.34.1