diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index e2e611a4d2c06bd567e9d5e353b3a4893623de6c..f7cc46d86591a220a183529a8f89456f9153385d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -190,7 +190,8 @@ static void
 qcom_ethqos_set_sgmii_loopback(struct qcom_ethqos *ethqos, bool enable)
 {
 	if (!ethqos->needs_sgmii_loopback ||
-	    ethqos->phy_mode != PHY_INTERFACE_MODE_2500BASEX)
+	    (ethqos->phy_mode != PHY_INTERFACE_MODE_2500BASEX &&
+	     ethqos->phy_mode != PHY_INTERFACE_MODE_SGMII))
 		return;
 
 	rgmii_updatel(ethqos,
@@ -637,6 +638,12 @@ static int ethqos_mac_finish_serdes(struct net_device *ndev, void *priv,
 
 	qcom_ethqos_set_sgmii_loopback(ethqos, false);
 
+	/* The interface mode is only known once phylink has resolved it and
+	 * may change at runtime, so keep it in sync for later
+	 * serdes_powerup() and qcom_ethqos_set_sgmii_loopback() calls.
+	 */
+	ethqos->phy_mode = interface;
+
 	if (interface == PHY_INTERFACE_MODE_SGMII ||
 	    interface == PHY_INTERFACE_MODE_2500BASEX)
 		ret = phy_set_mode_ext(ethqos->serdes_phy, PHY_MODE_ETHERNET,