[PATCH v3 05/17] net/dpaa2: fix link not up after port stop/start

[Maxime Leroy <maxime@leroys.fr>]

When LSC (Link State Change) interrupts are enabled, the link status
is only updated by interrupt events -- rte_eth_link_get_nowait() reads
the cached value without querying the hardware.

During dev_start(), dpaa2_dev_set_link_up() was called immediately
after dpni_enable(), before LSC interrupts were registered. The MAC
needs ~30ms to renegotiate after being re-enabled, so the initial
link query returned link down. By the time the link came up, the LSC
interrupt handler was not yet installed, so the link-up event was
missed and the cached link status remained down permanently.

The issue does not occur on the first dev_start() after probe because
dpni_reset() during probe does not bring the MAC down -- the kernel
dpmac driver keeps the physical link up. Only dpni_disable() during
dev_stop() causes the MAC to go down, requiring a full renegotiation
on the next dpni_enable().

The problem is more likely to occur with many queues: the queue setup
loop (dpni_get_queue for each RX queue) between dpni_enable() and the
LSC interrupt registration adds MC portal round-trips, giving the MAC
more time to complete negotiation before interrupts are armed. This
makes the link-up event more likely to be missed.

Move dpaa2_dev_set_link_up() after the LSC interrupt setup so that
any link-up event occurring during MAC negotiation is properly caught.

Fixes: c5acbb5ea20e ("net/dpaa2: support link status event")
Cc: stable@dpdk.org

Signed-off-by: Maxime Leroy <maxime@leroys.fr>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>
---
 drivers/net/dpaa2/dpaa2_ethdev.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/dpaa2/dpaa2_ethdev.c b/drivers/net/dpaa2/dpaa2_ethdev.c
index 3658e24dd2..e58b93c564 100644
--- a/drivers/net/dpaa2/dpaa2_ethdev.c
+++ b/drivers/net/dpaa2/dpaa2_ethdev.c
@@ -1391,9 +1391,6 @@ dpaa2_dev_start(struct rte_eth_dev *dev)
 		return ret;
 	}
 
-	/* Power up the phy. Needed to make the link go UP */
-	dpaa2_dev_set_link_up(dev);
-
 	for (i = 0; i < data->nb_rx_queues; i++) {
 		dpaa2_q = data->rx_queues[i];
 		ret = dpni_get_queue(dpni, CMD_PRI_LOW, priv->token,
@@ -1461,6 +1458,12 @@ dpaa2_dev_start(struct rte_eth_dev *dev)
 		dpaa2_eth_setup_irqs(dev, 1);
 	}
 
+	/* Power up the phy. Needed to make the link go UP.
+	 * Called after LSC interrupt setup so that the link-up
+	 * event is not missed if the MAC negotiates quickly.
+	 */
+	dpaa2_dev_set_link_up(dev);
+
 	/* Change the tx burst function if ordered queues are used */
 	if (priv->en_ordered)
 		dev->tx_pkt_burst = dpaa2_dev_tx_ordered;
-- 
2.43.0