[PATCH v2 3/3] net/mlx5: fix initial link status detection

[Dmitry Kozlyuk]

Link status change takes time that depends on the HW and the kernel.
It was checked immediately after the change was issued at probing.
If the port had beed down before probing, a "down" state may be read,
while the port would be "up" imminently.
After that, DPDK reported the port as "down" mistakenly
and "ifconfig $DEV up" did not trigger an LSC event,
because from the system's perspective the port was "up" already.

Install Netlink event handler at port probe before requesting the port
to come up in order to receive LSC event even if it comes up
between probe and start.

Fixes: b6499434b83e ("net/mlx5: fix link status initialization")
Cc: stable at dpdk.org

Signed-off-by: Dmitry Kozlyuk <dkozlyuk at nvidia.com>
Reviewed-by: Viacheslav Ovsiienko <viacheslavo at nvidia.com>
---
 drivers/net/mlx5/linux/mlx5_os.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index 29a4890d14..ff65efb2a2 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -1483,13 +1483,12 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	/* Bring Ethernet device up. */
 	DRV_LOG(DEBUG, "port %u forcing Ethernet interface up",
 		eth_dev->data->port_id);
-	mlx5_set_link_up(eth_dev);
-	/*
-	 * Even though the interrupt handler is not installed yet,
-	 * interrupts will still trigger on the async_fd from
-	 * Verbs context returned by ibv_open_device().
-	 */
+	/* Read link status in case it is up and there will be no event. */
 	mlx5_link_update(eth_dev, 0);
+	/* Watch LSC interrupts between port probe and port start. */
+	priv->sh->port[priv->dev_port - 1].nl_ih_port_id =
+							eth_dev->data->port_id;
+	mlx5_set_link_up(eth_dev);
 	for (i = 0; i < MLX5_FLOW_TYPE_MAXI; i++) {
 		icfg[i].release_mem_en = !!sh->config.reclaim_mode;
 		if (sh->config.reclaim_mode)
-- 
2.25.1