net-next: mediatek: properly handle RGMII modes

If an external Gigabit PHY is connected to either of the MACs we need to
be able to tell the PHY to use a delay. Not doing so will result in heavy
packet loss and/or data corruption when using PHYs such as the IC+ IP1001.
We tell the PHY which MII delay mode to use via the devictree.

The ethernet driver needs to be adapted to handle all 3 rgmii-*id modes
in the same way as normal rgmii when setting up the MAC.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -236,6 +236,9 @@ static int mtk_phy_connect(struct mtk_mac *mac)
 		return -ENODEV;
 
 	switch (of_get_phy_mode(np)) {
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+	case PHY_INTERFACE_MODE_RGMII_ID:
 	case PHY_INTERFACE_MODE_RGMII:
 		ge_mode = 0;
 		break;