From: Emil Tantilov <emil.s.tantilov@intel.com>
Date: Fri, 12 Jan 2018 14:02:56 -0800
Subject: ixgbe: don't set RXDCTL.RLPML for 82599
Patch-mainline: v4.16-rc1
Git-commit: 2bafa8fac19a31ca72ae1a3e48df35f73661dbed
References: bsc#1056657 FATE#322189

commit 2de6aa3a666e ("ixgbe: Add support for padding packet")

Uses RXDCTL.RLPML to limit the maximum frame size on Rx when using
build_skb. Unfortunately that register does not work on 82599.

Added an explicit check to avoid setting this register on 82599 MAC.

Extended the comment related to the setting of RXDCTL.RLPML to better
explain its purpose.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -3970,11 +3970,15 @@ void ixgbe_configure_rx_ring(struct ixgb
 		rxdctl &= ~0x3FFFFF;
 		rxdctl |=  0x080420;
 #if (PAGE_SIZE < 8192)
-	} else {
+	/* RXDCTL.RLPML does not work on 82599 */
+	} else if (hw->mac.type != ixgbe_mac_82599EB) {
 		rxdctl &= ~(IXGBE_RXDCTL_RLPMLMASK |
 			    IXGBE_RXDCTL_RLPML_EN);
 
-		/* Limit the maximum frame size so we don't overrun the skb */
+		/* Limit the maximum frame size so we don't overrun the skb.
+		 * This can happen in SRIOV mode when the MTU of the VF is
+		 * higher than the MTU of the PF.
+		 */
 		if (ring_uses_build_skb(ring) &&
 		    !test_bit(__IXGBE_RX_3K_BUFFER, &ring->state))
 			rxdctl |= IXGBE_MAX_2K_FRAME_BUILD_SKB |