ethernet/marvell: use core min/max MTU checking

mvneta: min_mtu 68, max_mtu 9676
- mtu validation routine mostly did range check, merge back into
  mvneta_change_mtu for simplicity

mvpp2: min_mtu 68, max_mtu 9676
- mtu validation routine mostly did range check, merge back into
  mvpp2_change_mtu for simplicity

pxa168_eth: min_mtu 68, max_mtu 9500

skge: min_mtu 60, max_mtu 9000

sky2: min_mtu 68, max_mtu 1500 or 9000, depending on hw

CC: netdev@vger.kernel.org
CC: Mirko Lindner <mlindner@marvell.com>
CC: Stephen Hemminger <stephen@networkplumber.org>
CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 5cb07c2..b85819e 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3024,29 +3024,6 @@ static void mvneta_stop_dev(struct mvneta_port *pp)
 	mvneta_rx_reset(pp);
 }
 
-/* Return positive if MTU is valid */
-static int mvneta_check_mtu_valid(struct net_device *dev, int mtu)
-{
-	if (mtu < 68) {
-		netdev_err(dev, "cannot change mtu to less than 68\n");
-		return -EINVAL;
-	}
-
-	/* 9676 == 9700 - 20 and rounding to 8 */
-	if (mtu > 9676) {
-		netdev_info(dev, "Illegal MTU value %d, round to 9676\n", mtu);
-		mtu = 9676;
-	}
-
-	if (!IS_ALIGNED(MVNETA_RX_PKT_SIZE(mtu), 8)) {
-		netdev_info(dev, "Illegal MTU value %d, rounding to %d\n",
-			mtu, ALIGN(MVNETA_RX_PKT_SIZE(mtu), 8));
-		mtu = ALIGN(MVNETA_RX_PKT_SIZE(mtu), 8);
-	}
-
-	return mtu;
-}
-
 static void mvneta_percpu_enable(void *arg)
 {
 	struct mvneta_port *pp = arg;
@@ -3067,9 +3044,11 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)
 	struct mvneta_port *pp = netdev_priv(dev);
 	int ret;
 
-	mtu = mvneta_check_mtu_valid(dev, mtu);
-	if (mtu < 0)
-		return -EINVAL;
+	if (!IS_ALIGNED(MVNETA_RX_PKT_SIZE(mtu), 8)) {
+		netdev_info(dev, "Illegal MTU value %d, rounding to %d\n",
+			    mtu, ALIGN(MVNETA_RX_PKT_SIZE(mtu), 8));
+		mtu = ALIGN(MVNETA_RX_PKT_SIZE(mtu), 8);
+	}
 
 	dev->mtu = mtu;
 
@@ -4154,6 +4133,11 @@ static int mvneta_probe(struct platform_device *pdev)
 	dev->priv_flags |= IFF_UNICAST_FLT | IFF_LIVE_ADDR_CHANGE;
 	dev->gso_max_segs = MVNETA_MAX_TSO_SEGS;
 
+	/* MTU range: 68 - 9676 */
+	dev->min_mtu = ETH_MIN_MTU;
+	/* 9676 == 9700 - 20 and rounding to 8 */
+	dev->max_mtu = 9676;
+
 	err = register_netdev(dev);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to register\n");