ixgbe: Fix DCB traffic class mapping for 82599

The traffic classes in hardware are not symmetrical for Rx and Tx.  Rx
is every 16 descriptor queues, Tx is not.  It runs 32-32-16-16-8-8-8 when
running with 8 traffic classes, and runs 64-32-16 when running with 4
traffic classes.  This patch fixes the mapping.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Cc: stable@kernel.org
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

@@ -2841,11 +2841,55 @@ static inline bool ixgbe_cache_ring_dcb(struct ixgbe_adapter *adapter)
 			}
 			ret = true;
 		} else if (adapter->hw.mac.type == ixgbe_mac_82599EB) {
-			for (i = 0; i < dcb_i; i++) {
+			if (dcb_i == 8) {
+				/*
+				 * Tx TC0 starts at: descriptor queue 0
+				 * Tx TC1 starts at: descriptor queue 32
+				 * Tx TC2 starts at: descriptor queue 64
+				 * Tx TC3 starts at: descriptor queue 80
+				 * Tx TC4 starts at: descriptor queue 96
+				 * Tx TC5 starts at: descriptor queue 104
+				 * Tx TC6 starts at: descriptor queue 112
+				 * Tx TC7 starts at: descriptor queue 120
+				 *
+				 * Rx TC0-TC7 are offset by 16 queues each
+				 */
+				for (i = 0; i < 3; i++) {
+					adapter->tx_ring[i].reg_idx = i << 5;
 					adapter->rx_ring[i].reg_idx = i << 4;
-				adapter->tx_ring[i].reg_idx = i << 4;
 				}
+				for ( ; i < 5; i++) {
+					adapter->tx_ring[i].reg_idx =
+					                         ((i + 2) << 4);
+					adapter->rx_ring[i].reg_idx = i << 4;
+				}
+				for ( ; i < dcb_i; i++) {
+					adapter->tx_ring[i].reg_idx =
+					                         ((i + 8) << 3);
+					adapter->rx_ring[i].reg_idx = i << 4;
+				}
+
 				ret = true;
+			} else if (dcb_i == 4) {
+				/*
+				 * Tx TC0 starts at: descriptor queue 0
+				 * Tx TC1 starts at: descriptor queue 64
+				 * Tx TC2 starts at: descriptor queue 96
+				 * Tx TC3 starts at: descriptor queue 112
+				 *
+				 * Rx TC0-TC3 are offset by 32 queues each
+				 */
+				adapter->tx_ring[0].reg_idx = 0;
+				adapter->tx_ring[1].reg_idx = 64;
+				adapter->tx_ring[2].reg_idx = 96;
+				adapter->tx_ring[3].reg_idx = 112;
+				for (i = 0 ; i < dcb_i; i++)
+					adapter->rx_ring[i].reg_idx = i << 5;
+
+				ret = true;
+			} else {
+				ret = false;
+			}
 		} else {
 			ret = false;
 		}