net: amd-xgbe: Reset link when the link never comes back

stable inclusion
from stable-5.10.20
commit 286fca3f30b94e359401c43a1ba13495cbcc6e24
bugzilla: 50608

--------------------------------

[ Upstream commit 84fe68eb ]

Normally, auto negotiation and reconnect should be automatically done by
the hardware. But there seems to be an issue where auto negotiation has
to be restarted manually. This happens because of link training and so
even though still connected to the partner the link never "comes back".
This needs an auto-negotiation restart.

Also, a change in xgbe-mdio is needed to get ethtool to recognize the
link down and get the link change message. This change is only
required in a backplane connection mode.

Fixes: abf0a1c2 ("amd-xgbe: Add support for SFP+ modules")
Co-developed-by: NSudheesh Mavila <sudheesh.mavila@amd.com>
Signed-off-by: NSudheesh Mavila <sudheesh.mavila@amd.com>
Signed-off-by: NShyam Sundar S K <Shyam-sundar.S-k@amd.com>
Acked-by: NTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/net/ethernet/amd/xgbe/xgbe-mdio.c

@@ -1345,7 +1345,7 @@ static void xgbe_phy_status(struct xgbe_prv_data *pdata)
 							     &an_restart);
 	if (an_restart) {
 		xgbe_phy_config_aneg(pdata);
-		return;
+		goto adjust_link;
 	}
 
 	if (pdata->phy.link) {

drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c

@@ -2610,6 +2610,14 @@ static int xgbe_phy_link_status(struct xgbe_prv_data *pdata, int *an_restart)
 	if (reg & MDIO_STAT1_LSTATUS)
 		return 1;
 
+	if (pdata->phy.autoneg == AUTONEG_ENABLE &&
+	    phy_data->port_mode == XGBE_PORT_MODE_BACKPLANE) {
+		if (!test_bit(XGBE_LINK_INIT, &pdata->dev_state)) {
+			netif_carrier_off(pdata->netdev);
+			*an_restart = 1;
+		}
+	}
+
 	/* No link, attempt a receiver reset cycle */
 	if (phy_data->rrc_count++ > XGBE_RRC_FREQUENCY) {
 		phy_data->rrc_count = 0;