usrp2: add a timeout to udp control and make it large for usrp2 control transactions

4 files changed, 30 insertions, 13 deletions

diff --git a/host/include/uhd/transport/udp_simple.hpp b/host/include/uhd/transport/udp_simple.hpp
index 98dca02f0..c84393ecf 100644
--- a/host/include/uhd/transport/udp_simple.hpp
+++ b/host/include/uhd/transport/udp_simple.hpp
@@ -73,9 +73,10 @@ public:
      * Receive into the provided buffer.
      * Blocks until data is received or a timeout occurs.
      * \param buff a mutable buffer to receive into
+     * \param timeout_ms the timeout in milliseconds
      * \return the number of bytes received or zero on timeout
      */
-    virtual size_t recv(const boost::asio::mutable_buffer &buff) = 0;
+    virtual size_t recv(const boost::asio::mutable_buffer &buff, size_t timeout_ms) = 0;
 };
 
 }} //namespace
diff --git a/host/lib/transport/udp_simple.cpp b/host/lib/transport/udp_simple.cpp
index f339127ad..89750f99d 100644
--- a/host/lib/transport/udp_simple.cpp
+++ b/host/lib/transport/udp_simple.cpp
@@ -34,12 +34,13 @@ using namespace uhd::transport;
  * This is okay bacause this is the slow-path implementation.
  *
  * \param socket the asio socket
+ * \param timeout_ms the timeout in milliseconds
  */
 static void reasonable_recv_timeout(
-    boost::asio::ip::udp::socket &socket
+    boost::asio::ip::udp::socket &socket, size_t timeout_ms
 ){
     boost::asio::deadline_timer timer(socket.get_io_service());
-    timer.expires_from_now(boost::posix_time::milliseconds(100));
+    timer.expires_from_now(boost::posix_time::milliseconds(timeout_ms));
     while (not (socket.available() or timer.expires_from_now().is_negative())){
         boost::this_thread::sleep(boost::posix_time::milliseconds(1));
     }
@@ -55,8 +56,8 @@ public:
     ~udp_connected_impl(void);
 
     //send/recv
-    size_t send(const boost::asio::const_buffer &buff);
-    size_t recv(const boost::asio::mutable_buffer &buff);
+    size_t send(const boost::asio::const_buffer &);
+    size_t recv(const boost::asio::mutable_buffer &, size_t);
 
 private:
     boost::asio::ip::udp::socket   *_socket;
@@ -85,8 +86,8 @@ size_t udp_connected_impl::send(const boost::asio::const_buffer &buff){
     return _socket->send(boost::asio::buffer(buff));
 }
 
-size_t udp_connected_impl::recv(const boost::asio::mutable_buffer &buff){
-    reasonable_recv_timeout(*_socket);
+size_t udp_connected_impl::recv(const boost::asio::mutable_buffer &buff, size_t timeout_ms){
+    reasonable_recv_timeout(*_socket, timeout_ms);
     if (not _socket->available()) return 0;
     return _socket->receive(boost::asio::buffer(buff));
 }
@@ -101,8 +102,8 @@ public:
     ~udp_broadcast_impl(void);
 
     //send/recv
-    size_t send(const boost::asio::const_buffer &buff);
-    size_t recv(const boost::asio::mutable_buffer &buff);
+    size_t send(const boost::asio::const_buffer &);
+    size_t recv(const boost::asio::mutable_buffer &, size_t);
 
 private:
     boost::asio::ip::udp::socket   *_socket;
@@ -136,8 +137,8 @@ size_t udp_broadcast_impl::send(const boost::asio::const_buffer &buff){
     return _socket->send_to(boost::asio::buffer(buff), _receiver_endpoint);
 }
 
-size_t udp_broadcast_impl::recv(const boost::asio::mutable_buffer &buff){
-    reasonable_recv_timeout(*_socket);
+size_t udp_broadcast_impl::recv(const boost::asio::mutable_buffer &buff, size_t timeout_ms){
+    reasonable_recv_timeout(*_socket, timeout_ms);
     if (not _socket->available()) return 0;
     boost::asio::ip::udp::endpoint sender_endpoint;
     return _socket->receive_from(boost::asio::buffer(buff), sender_endpoint);
diff --git a/host/lib/usrp/usrp2/usrp2_iface.cpp b/host/lib/usrp/usrp2/usrp2_iface.cpp
index eaaa722ac..a21157d76 100644
--- a/host/lib/usrp/usrp2/usrp2_iface.cpp
+++ b/host/lib/usrp/usrp2/usrp2_iface.cpp
@@ -28,6 +28,18 @@
 using namespace uhd;
 using namespace uhd::transport;
 
+/*!
+ * FIXME: large timeout, ethernet pause frames...
+ *
+ * Use a large timeout to work-around the fact that
+ * flow-control may throttle outgoing control packets
+ * due to its use of ethernet pause frames.
+ *
+ * This will be fixed when host-based flow control is implemented,
+ * along with larger incoming send buffers using the on-board SRAM.
+ */
+static const size_t CONTROL_TIMEOUT_MS = 3000; //3 seconds
+
 class usrp2_iface_impl : public usrp2_iface{
 public:
 /***********************************************************************
@@ -164,7 +176,7 @@ public:
         boost::uint8_t usrp2_ctrl_data_in_mem[udp_simple::mtu]; //allocate max bytes for recv
         const usrp2_ctrl_data_t *ctrl_data_in = reinterpret_cast<const usrp2_ctrl_data_t *>(usrp2_ctrl_data_in_mem);
         while(true){
-            size_t len = _ctrl_transport->recv(boost::asio::buffer(usrp2_ctrl_data_in_mem));
+            size_t len = _ctrl_transport->recv(boost::asio::buffer(usrp2_ctrl_data_in_mem), CONTROL_TIMEOUT_MS);
             if(len >= sizeof(boost::uint32_t) and ntohl(ctrl_data_in->proto_ver) != USRP2_PROTO_VERSION){
                 throw std::runtime_error(str(
                     boost::format("Expected protocol version %d, but got %d\n"
diff --git a/host/lib/usrp/usrp2/usrp2_impl.cpp b/host/lib/usrp/usrp2/usrp2_impl.cpp
index 02f53bc69..2c314c085 100644
--- a/host/lib/usrp/usrp2/usrp2_impl.cpp
+++ b/host/lib/usrp/usrp2/usrp2_impl.cpp
@@ -35,6 +35,9 @@ using namespace uhd::usrp;
 using namespace uhd::transport;
 namespace asio = boost::asio;
 
+//! wait this long for a control response when discovering devices
+static const size_t DISCOVERY_TIMEOUT_MS = 100;
+
 /***********************************************************************
  * Helper Functions
  **********************************************************************/
@@ -102,7 +105,7 @@ static uhd::device_addrs_t usrp2_find(const device_addr_t &hint){
     boost::uint8_t usrp2_ctrl_data_in_mem[udp_simple::mtu]; //allocate max bytes for recv
     const usrp2_ctrl_data_t *ctrl_data_in = reinterpret_cast<const usrp2_ctrl_data_t *>(usrp2_ctrl_data_in_mem);
     while(true){
-        size_t len = udp_transport->recv(asio::buffer(usrp2_ctrl_data_in_mem));
+        size_t len = udp_transport->recv(asio::buffer(usrp2_ctrl_data_in_mem), DISCOVERY_TIMEOUT_MS);
         //std::cout << len << "\n";
         if (len > offsetof(usrp2_ctrl_data_t, data)){
             //handle the received data