ixgbe: fix dca issue with relaxed ordering turned on

The is an issue where setting Relaxed Ordering (RO) bit
(in a PCI-E write transaction) on 82598 causing the chipset
to drop DCA hints.  This patch forces RO not to be set for
descriptors as well as payload.  This will only be in effect
while DCA is enabled and no performance difference was
noticed in testing.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_main.c

@@ -318,6 +318,9 @@ static void ixgbe_update_rx_dca(struct ixgbe_adapter *adapter,
 		rxctrl |= dca3_get_tag(&adapter->pdev->dev, cpu);
 		rxctrl |= IXGBE_DCA_RXCTRL_DESC_DCA_EN;
 		rxctrl |= IXGBE_DCA_RXCTRL_HEAD_DCA_EN;
+		rxctrl &= ~(IXGBE_DCA_RXCTRL_DESC_RRO_EN);
+		rxctrl &= ~(IXGBE_DCA_RXCTRL_DESC_WRO_EN |
+			    IXGBE_DCA_RXCTRL_DESC_HSRO_EN);
 		IXGBE_WRITE_REG(&adapter->hw, IXGBE_DCA_RXCTRL(q), rxctrl);
 		rx_ring->cpu = cpu;
 	}

drivers/net/ixgbe/ixgbe_type.h

@@ -404,6 +404,9 @@
 #define IXGBE_DCA_RXCTRL_DESC_DCA_EN (1 << 5) /* DCA Rx Desc enable */
 #define IXGBE_DCA_RXCTRL_HEAD_DCA_EN (1 << 6) /* DCA Rx Desc header enable */
 #define IXGBE_DCA_RXCTRL_DATA_DCA_EN (1 << 7) /* DCA Rx Desc payload enable */
+#define IXGBE_DCA_RXCTRL_DESC_RRO_EN (1 << 9) /* DCA Rx rd Desc Relax Order */
+#define IXGBE_DCA_RXCTRL_DESC_WRO_EN (1 << 13) /* DCA Rx wr Desc Relax Order */
+#define IXGBE_DCA_RXCTRL_DESC_HSRO_EN (1 << 15) /* DCA Rx Split Header RO */
 
 #define IXGBE_DCA_TXCTRL_CPUID_MASK 0x0000001F /* Tx CPUID Mask */
 #define IXGBE_DCA_TXCTRL_DESC_DCA_EN (1 << 5) /* DCA Tx Desc enable */