ethernet/atheros: use core min/max MTU checking

atl2: min_mtu 40, max_mtu 1504

- Remove a few redundant defines that already have equivalents in
  if_ether.h.

atl1: min_mtu 42, max_mtu 10218

atl1e: min_mtu 42, max_mtu 8170

atl1c: min_mtu 42, max_mtu 6122/1500

- GbE hardware gets a max_mtu of 6122, slower hardware gets 1500.

alx: min_mtu 34, max_mtu 9256

- Not so sure that minimum MTU number is really what was intended, but
  that's what the math actually makes it out to be, due to max_frame
  manipulations and comparison in alx_change_mtu, rather than just
  comparing new_mtu. (I think 68 was the intended min_mtu value).

CC: netdev@vger.kernel.org
CC: Jay Cliburn <jcliburn@gmail.com>
CC: Chris Snook <chris.snook@gmail.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/atheros/atlx/atl1.c b/drivers/net/ethernet/atheros/atlx/atl1.c
index 529bca7..9aede18 100644
--- a/drivers/net/ethernet/atheros/atlx/atl1.c
+++ b/drivers/net/ethernet/atheros/atlx/atl1.c
@@ -2701,23 +2701,15 @@ static void atl1_reset_dev_task(struct work_struct *work)
 static int atl1_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct atl1_adapter *adapter = netdev_priv(netdev);
-	int old_mtu = netdev->mtu;
 	int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
 
-	if ((max_frame < ETH_ZLEN + ETH_FCS_LEN) ||
-	    (max_frame > MAX_JUMBO_FRAME_SIZE)) {
-		if (netif_msg_link(adapter))
-			dev_warn(&adapter->pdev->dev, "invalid MTU setting\n");
-		return -EINVAL;
-	}
-
 	adapter->hw.max_frame_size = max_frame;
 	adapter->hw.tx_jumbo_task_th = (max_frame + 7) >> 3;
 	adapter->rx_buffer_len = (max_frame + 7) & ~7;
 	adapter->hw.rx_jumbo_th = adapter->rx_buffer_len / 8;
 
 	netdev->mtu = new_mtu;
-	if ((old_mtu != new_mtu) && netif_running(netdev)) {
+	if (netif_running(netdev)) {
 		atl1_down(adapter);
 		atl1_up(adapter);
 	}
@@ -3031,6 +3023,11 @@ static int atl1_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	/* is this valid? see atl1_setup_mac_ctrl() */
 	netdev->features |= NETIF_F_RXCSUM;
 
+	/* MTU range: 42 - 10218 */
+	netdev->min_mtu = ETH_ZLEN - (ETH_HLEN + VLAN_HLEN);
+	netdev->max_mtu = MAX_JUMBO_FRAME_SIZE -
+			  (ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN);
+
 	/*
 	 * patch for some L1 of old version,
 	 * the final version of L1 may not need these