qlcnic: Fix estimation of recv MSS in case of LRO

o Linux stack estimates MSS from skb->len or skb_shinfo(skb)->gso_size.
In case of LRO skb->len is aggregate of len of number of packets hence MSS
obtained using skb->len would be incorrect. Incorrect estimation of recv MSS
would lead to delayed acks in some traffic patterns (which sends two or three
packets and wait for ack and only then send remaining packets). This leads to
drop in performance. Hence we need to set gso_size to MSS obtained from firmware.

o This is fixed recently in firmware hence the MSS is obtained based on
capability. If fw is capable of sending the MSS then only driver sets the gso_size.
Signed-off-by: NRajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: NAnirban Chakraborty <anirban.chakraborty@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/qlogic/qlcnic/qlcnic.h

@@ -258,6 +258,8 @@ struct rcv_desc {
 	(((sts_data) >> 52) & 0x1)
 #define qlcnic_get_lro_sts_seq_number(sts_data)		\
 	((sts_data) & 0x0FFFFFFFF)
+#define qlcnic_get_lro_sts_mss(sts_data1)		\
+	((sts_data1 >> 32) & 0x0FFFF)
 
 
 struct status_desc {
@@ -623,6 +625,7 @@ struct qlcnic_recv_context {
 #define QLCNIC_CAP0_JUMBO_CONTIGUOUS	(1 << 7)
 #define QLCNIC_CAP0_LRO_CONTIGUOUS	(1 << 8)
 #define QLCNIC_CAP0_VALIDOFF		(1 << 11)
+#define QLCNIC_CAP0_LRO_MSS		(1 << 21)
 
 /*
  * Context state
@@ -829,6 +832,9 @@ struct qlcnic_mac_list_s {
 #define QLCNIC_FW_CAPABILITY_FVLANTX		BIT_9
 #define QLCNIC_FW_CAPABILITY_HW_LRO		BIT_10
 #define QLCNIC_FW_CAPABILITY_MULTI_LOOPBACK	BIT_27
+#define QLCNIC_FW_CAPABILITY_MORE_CAPS		BIT_31
+
+#define QLCNIC_FW_CAPABILITY_2_LRO_MAX_TCP_SEG	BIT_2
 
 /* module types */
 #define LINKEVENT_MODULE_NOT_PRESENT			1
@@ -918,6 +924,7 @@ struct qlcnic_ipaddr {
 #define QLCNIC_NEED_FLR			0x1000
 #define QLCNIC_FW_RESET_OWNER		0x2000
 #define QLCNIC_FW_HANG			0x4000
+#define QLCNIC_FW_LRO_MSS_CAP		0x8000
 #define QLCNIC_IS_MSI_FAMILY(adapter) \
 	((adapter)->flags & (QLCNIC_MSI_ENABLED | QLCNIC_MSIX_ENABLED))
 

drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c

@@ -237,6 +237,9 @@ qlcnic_fw_cmd_create_rx_ctx(struct qlcnic_adapter *adapter)
 						| QLCNIC_CAP0_VALIDOFF);
 	cap |= (QLCNIC_CAP0_JUMBO_CONTIGUOUS | QLCNIC_CAP0_LRO_CONTIGUOUS);
 
+	if (adapter->flags & QLCNIC_FW_LRO_MSS_CAP)
+		cap |= QLCNIC_CAP0_LRO_MSS;
+
 	prq->valid_field_offset = offsetof(struct qlcnic_hostrq_rx_ctx,
 							 msix_handler);
 	prq->txrx_sds_binding = nsds_rings - 1;

drivers/net/ethernet/qlogic/qlcnic/qlcnic_hdr.h

@@ -588,6 +588,7 @@ enum {
 #define CRB_DRIVER_VERSION		(QLCNIC_REG(0x2a0))
 
 #define CRB_FW_CAPABILITIES_1		(QLCNIC_CAM_RAM(0x128))
+#define CRB_FW_CAPABILITIES_2		(QLCNIC_CAM_RAM(0x12c))
 #define CRB_MAC_BLOCK_START		(QLCNIC_CAM_RAM(0x1c0))
 
 /*

drivers/net/ethernet/qlogic/qlcnic/qlcnic_init.c

@@ -1653,6 +1653,9 @@ qlcnic_process_lro(struct qlcnic_adapter *adapter,
 
 	length = skb->len;
 
+	if (adapter->flags & QLCNIC_FW_LRO_MSS_CAP)
+		skb_shinfo(skb)->gso_size = qlcnic_get_lro_sts_mss(sts_data1);
+
 	if (vid != 0xffff)
 		__vlan_hwaccel_put_tag(skb, vid);
 	netif_receive_skb(skb);

drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c

@@ -1136,6 +1136,8 @@ static int
 __qlcnic_up(struct qlcnic_adapter *adapter, struct net_device *netdev)
 {
 	int ring;
+	u32 capab2;
+
 	struct qlcnic_host_rds_ring *rds_ring;
 
 	if (adapter->is_up != QLCNIC_ADAPTER_UP_MAGIC)
@@ -1146,6 +1148,12 @@ __qlcnic_up(struct qlcnic_adapter *adapter, struct net_device *netdev)
 	if (qlcnic_set_eswitch_port_config(adapter))
 		return -EIO;
 
+	if (adapter->capabilities & QLCNIC_FW_CAPABILITY_MORE_CAPS) {
+		capab2 = QLCRD32(adapter, CRB_FW_CAPABILITIES_2);
+		if (capab2 & QLCNIC_FW_CAPABILITY_2_LRO_MAX_TCP_SEG)
+			adapter->flags |= QLCNIC_FW_LRO_MSS_CAP;
+	}
+
 	if (qlcnic_fw_create_ctx(adapter))
 		return -EIO;
 
@@ -1215,6 +1223,7 @@ __qlcnic_down(struct qlcnic_adapter *adapter, struct net_device *netdev)
 	qlcnic_napi_disable(adapter);
 
 	qlcnic_fw_destroy_ctx(adapter);
+	adapter->flags &= ~QLCNIC_FW_LRO_MSS_CAP;
 
 	qlcnic_reset_rx_buffers_list(adapter);
 	qlcnic_release_tx_buffers(adapter);