ixgbe: disable MSI-X by default on certain Cisco adapters

Due to an errata in 82598 parts MSI-X needs to be disabled
in certain ixgbe devices designed to transfer peer-to-peer
traffic on the PCIe bus. This patch sets the default
interrupt type to MSI rather than MSI-X for specific Cisco
ixgbe adapters.

Signed-off-by: Nicholas Nunley <nicholasx.d.nunley@intel.com>
Acked-by: John Ronciak <john.ronciak@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.h

@@ -104,6 +104,10 @@
 #define MAX_EMULATION_MAC_ADDRS         16
 #define VMDQ_P(p)   ((p) + adapter->num_vfs)
 
+#define IXGBE_SUBDEV_ID_82598AF_MEZZ		0x0049
+#define IXGBE_SUBDEV_ID_82598AF_MENLO_Q_MEZZ	0x004a
+#define IXGBE_SUBDEV_ID_82598AF_MENLO_E_MEZZ	0x004b
+
 struct vf_data_storage {
 	unsigned char vf_mac_addresses[ETH_ALEN];
 	u16 vf_mc_hashes[IXGBE_MAX_VF_MC_ENTRIES];

drivers/net/ixgbe/ixgbe_main.c

@@ -4314,6 +4314,9 @@ static int ixgbe_set_interrupt_capability(struct ixgbe_adapter *adapter)
 	int err = 0;
 	int vector, v_budget;
 
+	if (!(adapter->flags & IXGBE_FLAG_MSIX_CAPABLE))
+		goto try_msi;
+
 	/*
 	 * It's easy to be greedy for MSI-X vectors, but it really
 	 * doesn't do us much good if we have a lot more vectors
@@ -4345,7 +4348,7 @@ static int ixgbe_set_interrupt_capability(struct ixgbe_adapter *adapter)
 		if (adapter->flags & IXGBE_FLAG_MSIX_ENABLED)
 			goto out;
 	}
-
+try_msi:
 	adapter->flags &= ~IXGBE_FLAG_DCB_ENABLED;
 	adapter->flags &= ~IXGBE_FLAG_RSS_ENABLED;
 	adapter->flags &= ~IXGBE_FLAG_FDIR_HASH_CAPABLE;
@@ -4626,6 +4629,18 @@ static int __devinit ixgbe_sw_init(struct ixgbe_adapter *adapter)
 	adapter->ring_feature[RING_F_RSS].indices = rss;
 	adapter->flags |= IXGBE_FLAG_RSS_ENABLED;
 	adapter->ring_feature[RING_F_DCB].indices = IXGBE_MAX_DCB_INDICES;
+	adapter->flags |= IXGBE_FLAG_MSIX_CAPABLE;
+	if (adapter->hw.device_id == IXGBE_DEV_ID_82598AF_DUAL_PORT) {
+		switch (adapter->hw.subsystem_device_id) {
+		case IXGBE_SUBDEV_ID_82598AF_MEZZ:
+		case IXGBE_SUBDEV_ID_82598AF_MENLO_Q_MEZZ:
+		case IXGBE_SUBDEV_ID_82598AF_MENLO_E_MEZZ:
+			adapter->flags &= ~IXGBE_FLAG_MSIX_CAPABLE;
+			break;
+		default:
+			break;
+		}
+	}
 	if (hw->mac.type == ixgbe_mac_82598EB) {
 		if (hw->device_id == IXGBE_DEV_ID_82598AT)
 			adapter->flags |= IXGBE_FLAG_FAN_FAIL_CAPABLE;