TI DaVinci EMAC: Fix asymmetric handling of packets in NAPI Poll function.

The current implementation of NAPI poll function in the driver does not service
Rx packets, error condition even if a single Tx packet gets serviced in
the napi poll call. This behavior severely affects performance for specific use
cases. This patch modifies the poll function implementation to service tx/rx
packets in an identical manner.

Signed-off-by: Sriramakrishnan <srk@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/davinci_emac.c

@@ -2266,7 +2266,7 @@ static int emac_poll(struct napi_struct *napi, int budget)
 	struct net_device *ndev = priv->ndev;
 	struct device *emac_dev = &ndev->dev;
 	u32 status = 0;
-	u32 num_pkts = 0;
+	u32 num_tx_pkts = 0, num_rx_pkts = 0;
 
 	/* Check interrupt vectors and call packet processing */
 	status = emac_read(EMAC_MACINVECTOR);
@@ -2277,27 +2277,19 @@ static int emac_poll(struct napi_struct *napi, int budget)
 		mask = EMAC_DM646X_MAC_IN_VECTOR_TX_INT_VEC;
 
 	if (status & mask) {
-		num_pkts = emac_tx_bdproc(priv, EMAC_DEF_TX_CH,
+		num_tx_pkts = emac_tx_bdproc(priv, EMAC_DEF_TX_CH,
 					  EMAC_DEF_TX_MAX_SERVICE);
 	} /* TX processing */
 
-	if (num_pkts)
-		return budget;
-
 	mask = EMAC_DM644X_MAC_IN_VECTOR_RX_INT_VEC;
 
 	if (priv->version == EMAC_VERSION_2)
 		mask = EMAC_DM646X_MAC_IN_VECTOR_RX_INT_VEC;
 
 	if (status & mask) {
-		num_pkts = emac_rx_bdproc(priv, EMAC_DEF_RX_CH, budget);
+		num_rx_pkts = emac_rx_bdproc(priv, EMAC_DEF_RX_CH, budget);
 	} /* RX processing */
 
-	if (num_pkts < budget) {
-		napi_complete(napi);
-		emac_int_enable(priv);
-	}
-
 	mask = EMAC_DM644X_MAC_IN_VECTOR_HOST_INT;
 	if (priv->version == EMAC_VERSION_2)
 		mask = EMAC_DM646X_MAC_IN_VECTOR_HOST_INT;
@@ -2328,9 +2320,12 @@ static int emac_poll(struct napi_struct *napi, int budget)
 				dev_err(emac_dev, "RX Host error %s on ch=%d\n",
 					&emac_rxhost_errcodes[cause][0], ch);
 		}
-	} /* Host error processing */
+	} else if (num_rx_pkts < budget) {
+		napi_complete(napi);
+		emac_int_enable(priv);
+	}
 
-	return num_pkts;
+	return num_rx_pkts;
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER