ethernet/intel: use core min/max MTU checking

e100: min_mtu 68, max_mtu 1500
- remove e100_change_mtu entirely, is identical to old eth_change_mtu,
  and no longer serves a purpose. No need to set min_mtu or max_mtu
  explicitly, as ether_setup() will already set them to 68 and 1500.

e1000: min_mtu 46, max_mtu 16110

e1000e: min_mtu 68, max_mtu varies based on adapter

fm10k: min_mtu 68, max_mtu 15342
- remove fm10k_change_mtu entirely, does nothing now

i40e: min_mtu 68, max_mtu 9706

i40evf: min_mtu 68, max_mtu 9706

igb: min_mtu 68, max_mtu 9216
- There are two different "max" frame sizes claimed and both checked in
  the driver, the larger value wasn't relevant though, so I've set max_mtu
  to the smaller of the two values here to retain identical behavior.

igbvf: min_mtu 68, max_mtu 9216
- Same issue as igb duplicated

ixgb: min_mtu 68, max_mtu 16114
- Also remove pointless old == new check, as that's done in dev_set_mtu

ixgbe: min_mtu 68, max_mtu 9710

ixgbevf: min_mtu 68, max_mtu dependent on hardware/firmware
- Some hw can only handle up to max_mtu 1504 on a vf, others 9710

CC: netdev@vger.kernel.org
CC: intel-wired-lan@lists.osuosl.org
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -5974,19 +5974,12 @@ static int e1000_change_mtu(struct net_device *netdev, int new_mtu)
 	int max_frame = new_mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
 
 	/* Jumbo frame support */
-	if ((max_frame > (VLAN_ETH_FRAME_LEN + ETH_FCS_LEN)) &&
+	if ((new_mtu > ETH_DATA_LEN) &&
 	    !(adapter->flags & FLAG_HAS_JUMBO_FRAMES)) {
 		e_err("Jumbo Frames not supported.\n");
 		return -EINVAL;
 	}
 
-	/* Supported frame sizes */
-	if ((new_mtu < (VLAN_ETH_ZLEN + ETH_FCS_LEN)) ||
-	    (max_frame > adapter->max_hw_frame_size)) {
-		e_err("Unsupported MTU setting\n");
-		return -EINVAL;
-	}
-
 	/* Jumbo frame workaround on 82579 and newer requires CRC be stripped */
 	if ((adapter->hw.mac.type >= e1000_pch2lan) &&
 	    !(adapter->flags2 & FLAG2_CRC_STRIPPING) &&
@@ -7187,6 +7180,11 @@ static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		netdev->vlan_features |= NETIF_F_HIGHDMA;
 	}
 
+	/* MTU range: 68 - max_hw_frame_size */
+	netdev->min_mtu = ETH_MIN_MTU;
+	netdev->max_mtu = adapter->max_hw_frame_size -
+			  (VLAN_ETH_HLEN + ETH_FCS_LEN);
+
 	if (e1000e_enable_mng_pass_thru(&adapter->hw))
 		adapter->flags |= FLAG_MNG_PT_ENABLED;