net: macb: do not initialize mac_managed_pm on fixed link

In case of KSZ switch available on SAMA5D2 ICP some of SPI transfers
fails. This leaves the phy state machine in error state leading to
switch being unused after resume. By removing mac_managed_pm for
fixed links we rely on mdio_bus_phy_resume() being called later which
seems to work. This is only a temporary fix. Proper fix will need
to be done either on SPI or KSZ driver. This behavior was also present
in previous releases. A fixes tag hasn't been added as there no source
identified at the moment to blame.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

Author: claudiubeznea

drivers/net/ethernet/cadence/macb_main.c

@@ -868,7 +868,8 @@ static int macb_mii_probe(struct net_device *dev)
 
 	bp->phylink_config.dev = &dev->dev;
 	bp->phylink_config.type = PHYLINK_NETDEV;
-	bp->phylink_config.mac_managed_pm = true;
+	if (!of_phy_is_fixed_link(bp->pdev->dev.of_node))
+		bp->phylink_config.mac_managed_pm = true;
 
 	if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
 		bp->phylink_config.poll_fixed_state = true;