ixgbe: Disable Flow Control for certain devices

Flow Control autoneg should be disabled for certain adapters
that don't support autonegotiation of Flow Control at 10 gigabit.
These interfaces are the 10GBASE-T devices, CX4, and SFP+, all
running at 10 gigabit only.  1 gigabit is fine.
Signed-off-by: NPeter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_common.c

@@ -1783,6 +1783,20 @@ s32 ixgbe_fc_autoneg(struct ixgbe_hw *hw)
 		}
 	}
 
+	/*
+	 * Bail out on
+	 * - copper or CX4 adapters
+	 * - fiber adapters running at 10gig
+	 */
+	if ((hw->phy.media_type == ixgbe_media_type_copper) ||
+	     (hw->phy.media_type == ixgbe_media_type_cx4) ||
+	     ((hw->phy.media_type == ixgbe_media_type_fiber) &&
+	     (speed == IXGBE_LINK_SPEED_10GB_FULL))) {
+		hw->fc.fc_was_autonegged = false;
+		hw->fc.current_mode = hw->fc.requested_mode;
+		goto out;
+	}
+
 	/*
 	 * Read the AN advertisement and LP ability registers and resolve
 	 * local flow control settings accordingly