net: bcmgenet: Poll internal PHY for GENETv5

On GENETv5, there is a hardware issue which prevents the GENET hardware
from generating a link UP interrupt when the link is operating at
10Mbits/sec. Since we do not have any way to configure the link
detection logic, fallback to polling in that case.

Fixes: 4213808 ("net: bcmgenet: add support for the GENETv5 hardware")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmmii.c

@@ -321,9 +321,12 @@ int bcmgenet_mii_probe(struct net_device *dev)
 	phydev->advertising = phydev->supported;
 
 	/* The internal PHY has its link interrupts routed to the
-	 * Ethernet MAC ISRs
+	 * Ethernet MAC ISRs. On GENETv5 there is a hardware issue
+	 * that prevents the signaling of link UP interrupts when
+	 * the link operates at 10Mbps, so fallback to polling for
+	 * those versions of GENET.
 	 */
-	if (priv->internal_phy)
+	if (priv->internal_phy && !GENET_IS_V5(priv))
 		dev->phydev->irq = PHY_IGNORE_INTERRUPT;
 
 	return 0;