cxgb4: Free completed tx skbs promptly

Description of problem:
The NIC card is not reporting back to the driver the transmitted skbs,
so they get stuck in the TX ring causing issues with reference
counters in other kernel components.

Developed a new Automatic Egress Queue Update firmware facility to slowly tick
through Egress Queues and send back any outstanding CIDX Updates which are
laying around.

Based on original work by Casey Leedom <leedom@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -2303,7 +2303,8 @@ int t4_sge_alloc_eth_txq(struct adapter *adap, struct sge_eth_txq *txq,
 			    FW_EQ_ETH_CMD_PFN(adap->fn) | FW_EQ_ETH_CMD_VFN(0));
 	c.alloc_to_len16 = htonl(FW_EQ_ETH_CMD_ALLOC |
 				 FW_EQ_ETH_CMD_EQSTART | FW_LEN16(c));
-	c.viid_pkd = htonl(FW_EQ_ETH_CMD_VIID(pi->viid));
+	c.viid_pkd = htonl(FW_EQ_ETH_CMD_AUTOEQUEQE |
+			   FW_EQ_ETH_CMD_VIID(pi->viid));
 	c.fetchszm_to_iqid = htonl(FW_EQ_ETH_CMD_HOSTFCMODE(2) |
 				   FW_EQ_ETH_CMD_PCIECHN(pi->tx_chan) |
 				   FW_EQ_ETH_CMD_FETCHRO(1) |

drivers/net/ethernet/chelsio/cxgb4/t4fw_api.h

@@ -1227,6 +1227,7 @@ struct fw_eq_eth_cmd {
 #define FW_EQ_ETH_CMD_CIDXFTHRESH(x) ((x) << 16)
 #define FW_EQ_ETH_CMD_EQSIZE(x) ((x) << 0)
 
+#define FW_EQ_ETH_CMD_AUTOEQUEQE (1U << 30)
 #define FW_EQ_ETH_CMD_VIID(x) ((x) << 16)
 
 struct fw_eq_ctrl_cmd {

drivers/net/ethernet/chelsio/cxgb4vf/sge.c

@@ -2250,7 +2250,8 @@ int t4vf_sge_alloc_eth_txq(struct adapter *adapter, struct sge_eth_txq *txq,
 	cmd.alloc_to_len16 = cpu_to_be32(FW_EQ_ETH_CMD_ALLOC |
 					 FW_EQ_ETH_CMD_EQSTART |
 					 FW_LEN16(cmd));
-	cmd.viid_pkd = cpu_to_be32(FW_EQ_ETH_CMD_VIID(pi->viid));
+	cmd.viid_pkd = cpu_to_be32(FW_EQ_ETH_CMD_AUTOEQUEQE |
+				   FW_EQ_ETH_CMD_VIID(pi->viid));
 	cmd.fetchszm_to_iqid =
 		cpu_to_be32(FW_EQ_ETH_CMD_HOSTFCMODE(SGE_HOSTFCMODE_STPG) |
 			    FW_EQ_ETH_CMD_PCIECHN(pi->port_id) |