device3: Constraint send/recv_frame_size based on down/upstream MTU

We need to properly contraint the send/recv_frame_size based on the
minimum MTU of all the down/upstream blocks. This fixes the issue with
E310 tx/rx streaming as it has smaller MTU sizes than the other usrps.

11 files changed, 108 insertions, 6 deletions

diff --git a/host/lib/rfnoc/block_ctrl_base.cpp b/host/lib/rfnoc/block_ctrl_base.cpp
index ed8068b5b..e70267b96 100644
--- a/host/lib/rfnoc/block_ctrl_base.cpp
+++ b/host/lib/rfnoc/block_ctrl_base.cpp
@@ -94,12 +94,16 @@ block_ctrl_base::block_ctrl_base(const make_args_t& make_args)
         // Set source addresses:
         sr_write(SR_BLOCK_SID, get_address(ctrl_port), ctrl_port);
         // Set sink buffer sizes:
-        settingsbus_reg_t reg = SR_READBACK_REG_FIFOSIZE;
-        size_t buf_size_bytes = size_t(sr_read64(reg, ctrl_port));
+        settingsbus_reg_t reg_fifo = SR_READBACK_REG_FIFOSIZE;
+        size_t buf_size_bytes      = size_t(sr_read64(reg_fifo, ctrl_port));
         if (buf_size_bytes > 0)
             n_valid_input_buffers++;
         _tree->create<size_t>(_root_path / "input_buffer_size" / ctrl_port)
             .set(buf_size_bytes);
+        // Set MTU size and convert to bytes:
+        settingsbus_reg_t reg_mtu = SR_READBACK_REG_MTU;
+        size_t mtu                = 8 * (1 << size_t(sr_read64(reg_mtu, ctrl_port)));
+        _tree->create<size_t>(_root_path / "mtu" / ctrl_port).set(mtu);
         // Set default destination SIDs
         // Otherwise, the default is someone else's SID, which we don't want
         sr_write(SR_RESP_IN_DST_SID, 0xFFFF, ctrl_port);
diff --git a/host/lib/rfnoc/sink_block_ctrl_base.cpp b/host/lib/rfnoc/sink_block_ctrl_base.cpp
index bb81706f9..f1d65350a 100644
--- a/host/lib/rfnoc/sink_block_ctrl_base.cpp
+++ b/host/lib/rfnoc/sink_block_ctrl_base.cpp
@@ -43,11 +43,19 @@ std::vector<size_t> sink_block_ctrl_base::get_input_ports() const
  **********************************************************************/
 size_t sink_block_ctrl_base::get_fifo_size(size_t block_port) const
 {
-    if (_tree->exists(
-            _root_path / "input_buffer_size" / str(boost::format("%d") % block_port))) {
+    if (_tree->exists(_root_path / "input_buffer_size" / std::to_string(block_port))) {
         return _tree
             ->access<size_t>(
-                _root_path / "input_buffer_size" / str(boost::format("%d") % block_port))
+                _root_path / "input_buffer_size" / std::to_string(block_port))
+            .get();
+    }
+    return 0;
+}
+
+size_t sink_block_ctrl_base::get_mtu(size_t block_port) const
+{
+    if (_tree->exists(_root_path / "mtu" / std::to_string(block_port))) {
+        return _tree->access<size_t>(_root_path / "mtu" / std::to_string(block_port))
             .get();
     }
     return 0;
diff --git a/host/lib/rfnoc/source_block_ctrl_base.cpp b/host/lib/rfnoc/source_block_ctrl_base.cpp
index 656ab26af..d06b6632d 100644
--- a/host/lib/rfnoc/source_block_ctrl_base.cpp
+++ b/host/lib/rfnoc/source_block_ctrl_base.cpp
@@ -143,6 +143,16 @@ void source_block_ctrl_base::configure_flow_control_out(const bool enable_fc_out
     sr_write(SR_FLOW_CTRL_EN, config, block_port);
 }
 
+size_t source_block_ctrl_base::get_mtu(size_t block_port) const
+{
+    if (_tree->exists(_root_path / "mtu" / std::to_string(block_port))) {
+        return _tree->access<size_t>(_root_path / "mtu" / std::to_string(block_port))
+            .get();
+    }
+    return 0;
+}
+
+
 /***********************************************************************
  * Hooks
  **********************************************************************/
diff --git a/host/lib/usrp/device3/device3_impl.hpp b/host/lib/usrp/device3/device3_impl.hpp
index 3bf6f6111..62fd399ac 100644
--- a/host/lib/usrp/device3/device3_impl.hpp
+++ b/host/lib/usrp/device3/device3_impl.hpp
@@ -206,6 +206,9 @@ protected:
     //! Is called after a streamer is generated
     virtual void post_streamer_hooks(uhd::direction_t) {}
 
+    //! get mtu
+    virtual size_t get_mtu(const size_t, const uhd::direction_t) = 0;
+
     /***********************************************************************
      * Channel-related
      **********************************************************************/
diff --git a/host/lib/usrp/device3/device3_io_impl.cpp b/host/lib/usrp/device3/device3_io_impl.cpp
index ce8ff2cbf..081f881d5 100644
--- a/host/lib/usrp/device3/device3_io_impl.cpp
+++ b/host/lib/usrp/device3/device3_io_impl.cpp
@@ -338,6 +338,33 @@ rx_streamer::sptr device3_impl::get_rx_stream(const stream_args_t& args_)
         // Setup the DSP transport hints
         device_addr_t rx_hints = get_rx_hints(mb_index);
 
+        // Traverse the upstream nodes for minimum mtu
+        size_t min_mtu = blk_ctrl->get_mtu(block_port);
+        UHD_RX_STREAMER_LOG() << "Maximum MTU supported by " <<  blk_ctrl->unique_id()
+                    << ": " << min_mtu;
+        std::vector<boost::shared_ptr<uhd::rfnoc::source_block_ctrl_base>>
+            upstream_source_nodes =
+                blk_ctrl->find_upstream_node<uhd::rfnoc::source_block_ctrl_base>();
+        for (const boost::shared_ptr<uhd::rfnoc::source_block_ctrl_base>& node :
+            upstream_source_nodes) {
+            // Get MTU from Port 0 of the upstream nodes. This is okay for now as
+            // currently we use port 0 of a block in case of channel 1.
+            UHD_RX_STREAMER_LOG() << "Maximum MTU supported by " << node->unique_id()
+                    << ": " << node->get_mtu(0);
+            min_mtu = std::min(min_mtu, node->get_mtu(0));
+        }
+        // Contraint min_mtu by device mtu
+        min_mtu = std::min(min_mtu, get_mtu(mb_index, uhd::direction_t::RX_DIRECTION));
+        if (rx_hints.has_key("recv_frame_size")) {
+            if (rx_hints.cast<size_t>("recv_frame_size", min_mtu) > min_mtu) {
+                UHD_RX_STREAMER_LOG() << "Requested recv_frame_size of " << rx_hints["recv_frame_size"]
+                    << " exceeds the maximum possible on this stream. Using " << min_mtu;
+            }
+            min_mtu =
+                std::min(min_mtu, rx_hints.cast<size_t>("recv_frame_size", min_mtu));
+        }
+        rx_hints["recv_frame_size"] = std::to_string(min_mtu);
+
         // allocate sid and create transport
         uhd::sid_t stream_address = blk_ctrl->get_address(block_port);
         UHD_RX_STREAMER_LOG() << "creating rx stream " << rx_hints.to_string();
@@ -577,6 +604,33 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t& args_)
 
         // Setup the dsp transport hints
         device_addr_t tx_hints = get_tx_hints(mb_index);
+
+        // Traverse the downstream nodes for minimum mtu
+        size_t min_mtu = blk_ctrl->get_mtu(block_port);
+        UHD_TX_STREAMER_LOG() << "Maximum MTU supported by " <<  blk_ctrl->unique_id()
+                    << ": " << min_mtu;
+        std::vector<boost::shared_ptr<uhd::rfnoc::sink_block_ctrl_base>>
+            downstream_sink_nodes =
+                blk_ctrl->find_downstream_node<uhd::rfnoc::sink_block_ctrl_base>();
+        for (const boost::shared_ptr<uhd::rfnoc::sink_block_ctrl_base>& node :
+            downstream_sink_nodes) {
+            // Get MTU from Port 0 of the downstream nodes. This is okay for now as
+            // currently we use port 0 of a block in case of channel 1.
+            UHD_TX_STREAMER_LOG() << "Maximum MTU supported by " <<  node->unique_id()
+                    << ": " << node->get_mtu(0);
+            min_mtu = std::min(min_mtu, node->get_mtu(0));
+        }
+        min_mtu = std::min(min_mtu, get_mtu(mb_index, uhd::direction_t::TX_DIRECTION));
+        if (tx_hints.has_key("send_frame_size")) {
+            if (tx_hints.cast<size_t>("send_frame_size", min_mtu) > min_mtu) {
+                UHD_TX_STREAMER_LOG() << "Requested send_frame_size of " << tx_hints["send_frame_size"]
+                    << " exceeds the maximum possible on this stream. Using " << min_mtu;
+            }
+            min_mtu =
+                std::min(min_mtu, tx_hints.cast<size_t>("send_frame_size", min_mtu));
+        }
+        tx_hints["send_frame_size"] = std::to_string(min_mtu);
+
         const size_t fifo_size = blk_ctrl->get_fifo_size(block_port);
         // Allocate sid and create transport
         uhd::sid_t stream_address = blk_ctrl->get_address(block_port);
diff --git a/host/lib/usrp/e300/e300_impl.cpp b/host/lib/usrp/e300/e300_impl.cpp
index 59a8cec88..5a6376039 100644
--- a/host/lib/usrp/e300/e300_impl.cpp
+++ b/host/lib/usrp/e300/e300_impl.cpp
@@ -731,6 +731,11 @@ uhd::both_xports_t e300_impl::make_transport(
     return xports;
 }
 
+size_t e300_impl::get_mtu(const size_t /*mb_index*/, const uhd::direction_t dir) {
+    return (dir == RX_DIRECTION) ? _data_xport_params.recv_frame_size :
+            _data_xport_params.send_frame_size;
+}
+
 void e300_impl::_update_clock_source(const std::string &source)
 {
     if (source != "internal") {
diff --git a/host/lib/usrp/e300/e300_impl.hpp b/host/lib/usrp/e300/e300_impl.hpp
index 2e919cf9b..0a6f153eb 100644
--- a/host/lib/usrp/e300/e300_impl.hpp
+++ b/host/lib/usrp/e300/e300_impl.hpp
@@ -166,6 +166,9 @@ private: // methods
         return uhd::ENDIANNESS_LITTLE;
     };
 
+    //! get mtu
+    size_t get_mtu(const size_t, const uhd::direction_t);
+
     /************************************************************************
      * Helpers
      ***********************************************************************/
diff --git a/host/lib/usrp/mpmd/mpmd_impl.cpp b/host/lib/usrp/mpmd/mpmd_impl.cpp
index b8ce6cabd..2f3584498 100644
--- a/host/lib/usrp/mpmd/mpmd_impl.cpp
+++ b/host/lib/usrp/mpmd/mpmd_impl.cpp
@@ -348,6 +348,10 @@ void mpmd_impl::setup_rpc_blocks(
     }
 }
 
+size_t mpmd_impl::get_mtu(const size_t mb_index, const uhd::direction_t dir) {
+    return _mb[mb_index]->get_mtu(dir);
+}
+
 /*****************************************************************************
  * Factory & Registry
  ****************************************************************************/
diff --git a/host/lib/usrp/mpmd/mpmd_impl.hpp b/host/lib/usrp/mpmd/mpmd_impl.hpp
index f74627afa..bdb6bd691 100644
--- a/host/lib/usrp/mpmd/mpmd_impl.hpp
+++ b/host/lib/usrp/mpmd/mpmd_impl.hpp
@@ -246,6 +246,9 @@ public:
         uhd::usrp::device3_impl::xport_type_t,
         const uhd::device_addr_t&);
 
+    //! get mtu
+    size_t get_mtu(const size_t, const uhd::direction_t);
+
 private:
     uhd::device_addr_t get_rx_hints(size_t mb_index);
     uhd::device_addr_t get_tx_hints(size_t mb_index);
diff --git a/host/lib/usrp/x300/x300_impl.cpp b/host/lib/usrp/x300/x300_impl.cpp
index 796d422ad..b9b4a06f9 100644
--- a/host/lib/usrp/x300/x300_impl.cpp
+++ b/host/lib/usrp/x300/x300_impl.cpp
@@ -1526,7 +1526,7 @@ uhd::both_xports_t x300_impl::make_transport(const uhd::sid_t& address,
             // Increasing number of recv frames here because ctrl_iface uses it
             // to determine how many control packets can be in flight before it
             // must wait for an ACK
-            default_buff_args.num_recv_frames = 
+            default_buff_args.num_recv_frames =
                 uhd::rfnoc::CMD_FIFO_SIZE / uhd::rfnoc::MAX_CMD_PKT_SIZE;
         } else if (xport_type == TX_DATA) {
             size_t default_frame_size = conn.link_rate == x300::MAX_RATE_1GIGE
@@ -1993,6 +1993,11 @@ x300_impl::frame_size_t x300_impl::determine_max_frame_size(
     return frame_size;
 }
 
+size_t x300_impl::get_mtu(const size_t /*mb_index*/, const uhd::direction_t dir) {
+    return (dir == RX_DIRECTION) ? _max_frame_sizes.recv_frame_size :
+            _max_frame_sizes.send_frame_size;
+}
+
 /***********************************************************************
  * compat checks
  **********************************************************************/
diff --git a/host/lib/usrp/x300/x300_impl.hpp b/host/lib/usrp/x300/x300_impl.hpp
index c101b3032..8d50f9914 100644
--- a/host/lib/usrp/x300/x300_impl.hpp
+++ b/host/lib/usrp/x300/x300_impl.hpp
@@ -173,6 +173,9 @@ private:
         const xport_type_t xport_type,
         const uhd::device_addr_t& args);
 
+    //! get mtu
+    size_t get_mtu(const size_t, const uhd::direction_t);
+
     struct frame_size_t
     {
         size_t recv_frame_size;