net: stmmac: Power up SERDES after the PHY link

The Tegra MGBE ethernet controller requires that the SERDES link is
powered-up after the PHY link is up, otherwise the link fails to
become ready following a resume from suspend. Add a variable to indicate
that the SERDES link must be powered-up after the PHY link.
Signed-off-by: Revanth Kumar Uppala <ruppala@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -988,6 +988,9 @@ static void stmmac_mac_link_up(struct phylink_config *config,
 	struct stmmac_priv *priv = netdev_priv(to_net_dev(config->dev));
 	u32 old_ctrl, ctrl;
 
+	if (priv->plat->serdes_up_after_phy_linkup && priv->plat->serdes_powerup)
+		priv->plat->serdes_powerup(priv->dev, priv->plat->bsp_priv);
+
 	old_ctrl = readl(priv->ioaddr + MAC_CTRL_REG);
 	ctrl = old_ctrl & ~priv->hw->link.speed_mask;
 
@@ -3809,7 +3812,7 @@ static int __stmmac_open(struct net_device *dev,
 
 	stmmac_reset_queues_param(priv);
 
-	if (priv->plat->serdes_powerup) {
+	if (!priv->plat->serdes_up_after_phy_linkup && priv->plat->serdes_powerup) {
 		ret = priv->plat->serdes_powerup(dev, priv->plat->bsp_priv);
 		if (ret < 0) {
 			netdev_err(priv->dev, "%s: Serdes powerup failed\n",
@@ -7518,7 +7521,7 @@ int stmmac_resume(struct device *dev)
 			stmmac_mdio_reset(priv->mii);
 	}
 
-	if (priv->plat->serdes_powerup) {
+	if (!priv->plat->serdes_up_after_phy_linkup && priv->plat->serdes_powerup) {
 		ret = priv->plat->serdes_powerup(ndev,
 						 priv->plat->bsp_priv);
 

include/linux/stmmac.h

@@ -271,5 +271,6 @@ struct plat_stmmacenet_data {
 	int msi_tx_base_vec;
 	bool use_phy_wol;
 	bool sph_disable;
+	bool serdes_up_after_phy_linkup;
 };
 #endif