[PATCH v4 15/20] net/txgbe: fix FEC mode configuration on 25G NIC

[Zaiyu Wang <zaiyuwang@trustnetic.com>]

The 25G NIC offers off, RS, Base-R, and auto FEC modes. When
reconfiguring the PHY, the FEC mode must match on both sides;
otherwise, the link cannot come up. The current driver fails to
maintain this requirement, causing link instability.

Add proper FEC mode handling during PHY reconfiguration to
guarantee link establishment.

Fixes: fb6eb170dfa2 ("net/txgbe: add basic link configuration for Amber-Lite")
Cc: stable@dpdk.org

Signed-off-by: Zaiyu Wang <zaiyuwang@trustnetic.com>
---
 drivers/net/txgbe/base/txgbe_aml.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/txgbe/base/txgbe_aml.c b/drivers/net/txgbe/base/txgbe_aml.c
index a5b9d951ea..fbb09d144b 100644
--- a/drivers/net/txgbe/base/txgbe_aml.c
+++ b/drivers/net/txgbe/base/txgbe_aml.c
@@ -282,6 +282,14 @@ s32 txgbe_setup_phy_link_aml(struct txgbe_hw *hw,
 	    !(hw->fec_mode & hw->cur_fec_link)))
 		goto out;
 
+	if (speed == TXGBE_LINK_SPEED_25GB_FULL &&
+	    link_speed == TXGBE_LINK_SPEED_25GB_FULL) {
+		txgbe_e56_fec_polling(hw, &link_up);
+
+		if (link_up)
+			goto out;
+	}
+
 	rte_spinlock_lock(&hw->phy_lock);
 	ret_status = txgbe_set_link_to_amlite(hw, speed);
 	rte_spinlock_unlock(&hw->phy_lock);
@@ -360,7 +368,10 @@ static s32 txgbe_setup_mac_link_multispeed_fiber_aml(struct txgbe_hw *hw,
 		/* If we already have link at this speed, just jump out */
 		txgbe_e56_check_phy_link(hw, &link_speed, &link_up);
 
-		if (link_speed == TXGBE_LINK_SPEED_25GB_FULL && link_up)
+		hw->cur_fec_link = txgbe_phy_fec_get(hw);
+
+		if (link_speed == TXGBE_LINK_SPEED_25GB_FULL && link_up &&
+		    hw->fec_mode & hw->cur_fec_link)
 			goto out;
 
 		/* Allow module to change analog characteristics (10G -> 25G) */
-- 
2.21.0.windows.1