net/tcp/handshake: send the SYN immediately.

Change-Id: I761cff3b9950b75327fa03fb53b861ea088d8b35
Signed-off-by: chao.an <anchao@xiaomi.com>

net/tcp/tcp_conn.c

@@ -1283,7 +1283,7 @@ int tcp_connect(FAR struct tcp_conn_s *conn, FAR const struct sockaddr *addr)
 
   conn->tx_unacked = 1;    /* TCP length of the SYN is one. */
   conn->nrtx       = 0;
-  conn->timer      = 1;    /* Send the SYN next time around. */
+  conn->timer      = 0;    /* Send the SYN immediately. */
   conn->rto        = TCP_RTO;
   conn->sa         = 0;
   conn->sv         = 16;   /* Initial value of the RTT variance. */

net/tcp/tcp_connect.c

@@ -41,6 +41,7 @@
 #include <nuttx/net/tcp.h>
 
 #include "devif/devif.h"
+#include "netdev/netdev.h"
 #include "socket/socket.h"
 #include "tcp/tcp.h"
 
@@ -322,6 +323,10 @@ int psock_tcp_connect(FAR struct socket *psock,
       ret = psock_setup_callbacks(psock, &state);
       if (ret >= 0)
         {
+          /* Notify the device driver that new connection is available. */
+
+          netdev_txnotify_dev(((FAR struct tcp_conn_s *)psock->s_conn)->dev);
+
           /* Wait for either the connect to complete or for an error/timeout
            * to occur. NOTES:  net_lockedwait will also terminate if a signal
            * is received.