3 files changed, 69 insertions, 30 deletions
diff --git a/host/lib/usrp/x300/x300_eth_mgr.cpp b/host/lib/usrp/x300/x300_eth_mgr.cpp
index f428fc98e..dcc8195ae 100644
--- a/host/lib/usrp/x300/x300_eth_mgr.cpp
+++ b/host/lib/usrp/x300/x300_eth_mgr.cpp
@@ -20,6 +20,7 @@
 #include <uhd/transport/udp_zero_copy.hpp>
 #include <uhd/utils/algorithm.hpp>
 #include <uhd/utils/byteswap.hpp>
+#include <uhd/utils/cast.hpp>
 #include <uhdlib/rfnoc/device_id.hpp>
 #include <uhdlib/rfnoc/rfnoc_common.hpp>
 #include <uhdlib/transport/udp_boost_asio_link.hpp>
@@ -227,6 +228,10 @@ both_links_t eth_manager::get_links(link_type_t link_type,
     x300_eth_conn_t conn = eth_conns[local_device_id];
     zero_copy_xport_params default_buff_args;
 
+    const bool enable_fc = not link_args.has_key("enable_fc")
+                           || uhd::cast::from_str<bool>(link_args.get("enable_fc"));
+    const bool lossy_xport = enable_fc;
+
     const size_t send_mtu = get_mtu(uhd::TX_DIRECTION);
     const size_t recv_mtu = get_mtu(uhd::RX_DIRECTION);
 
@@ -278,8 +283,9 @@ both_links_t eth_manager::get_links(link_type_t link_type,
             link_params.send_buff_size,
             link,
             link_params.recv_buff_size,
+            lossy_xport,
             true,
-            true);
+            enable_fc);
 #else
         UHD_LOG_WARNING("X300", "Cannot create DPDK transport, falling back to UDP");
 #endif
@@ -289,8 +295,13 @@ both_links_t eth_manager::get_links(link_type_t link_type,
         link_params,
         link_params.recv_buff_size,
         link_params.send_buff_size);
-    return std::make_tuple(
-        link, link_params.send_buff_size, link, link_params.recv_buff_size, true, false);
+    return std::make_tuple(link,
+        link_params.send_buff_size,
+        link,
+        link_params.recv_buff_size,
+        lossy_xport,
+        false,
+        enable_fc);
 }
 
 /******************************************************************************
diff --git a/host/lib/usrp/x300/x300_mb_iface.cpp b/host/lib/usrp/x300/x300_mb_iface.cpp
index c89374f82..a351864df 100644
--- a/host/lib/usrp/x300/x300_mb_iface.cpp
+++ b/host/lib/usrp/x300/x300_mb_iface.cpp
@@ -98,12 +98,17 @@ uhd::rfnoc::chdr_ctrl_xport::sptr x300_impl::x300_mb_iface::make_ctrl_transport(
     send_link_if::sptr send_link;
     recv_link_if::sptr recv_link;
     bool lossy_xport;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, lossy_xport, std::ignore) =
-        _conn_mgr->get_links(link_type_t::CTRL,
-            local_device_id,
-            local_epid,
-            uhd::rfnoc::sep_id_t(),
-            uhd::device_addr_t());
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        std::ignore,
+        lossy_xport,
+        std::ignore,
+        std::ignore) = _conn_mgr->get_links(link_type_t::CTRL,
+        local_device_id,
+        local_epid,
+        uhd::rfnoc::sep_id_t(),
+        uhd::device_addr_t());
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_device_id] = send_link->get_send_adapter_id();
@@ -142,13 +147,18 @@ uhd::rfnoc::chdr_rx_data_xport::uptr x300_impl::x300_mb_iface::make_rx_data_tran
     send_link_if::sptr send_link;
     recv_link_if::sptr recv_link;
     size_t recv_buff_size;
-    bool lossy_xport, packet_fc;
-    std::tie(send_link, std::ignore, recv_link, recv_buff_size, lossy_xport, packet_fc) =
-        _conn_mgr->get_links(link_type_t::RX_DATA,
-            local_sep_addr.first,
-            local_epid,
-            remote_epid,
-            xport_args);
+    bool lossy_xport, packet_fc, enable_fc;
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        recv_buff_size,
+        lossy_xport,
+        packet_fc,
+        enable_fc) = _conn_mgr->get_links(link_type_t::RX_DATA,
+        local_sep_addr.first,
+        local_epid,
+        remote_epid,
+        xport_args);
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_sep_addr.first] = send_link->get_send_adapter_id();
@@ -159,14 +169,19 @@ uhd::rfnoc::chdr_rx_data_xport::uptr x300_impl::x300_mb_iface::make_rx_data_tran
 
     const double ratio = 1.0 / 32;
 
-    // Configure flow control frequency to use either bytes only or packets only
     uhd::rfnoc::stream_buff_params_t fc_freq;
-    if (packet_fc) {
-        fc_freq = {uhd::rfnoc::MAX_FC_FREQ_BYTES,
-            static_cast<uint32_t>(std::ceil(recv_link->get_num_recv_frames() * ratio))};
+    if (enable_fc) {
+        // Configure flow control frequency to use either bytes only or packets only
+        if (packet_fc) {
+            fc_freq = {uhd::rfnoc::MAX_FC_FREQ_BYTES,
+                static_cast<uint32_t>(
+                    std::ceil(recv_link->get_num_recv_frames() * ratio))};
+        } else {
+            fc_freq = {static_cast<uint64_t>(std::ceil(double(recv_buff_size) * ratio)),
+                uhd::rfnoc::MAX_FC_FREQ_PKTS};
+        }
     } else {
-        fc_freq = {static_cast<uint64_t>(std::ceil(double(recv_buff_size) * ratio)),
-            uhd::rfnoc::MAX_FC_FREQ_PKTS};
+        fc_freq = {0, 0};
     }
 
     uhd::rfnoc::stream_buff_params_t fc_headroom = {0, 0};
@@ -235,12 +250,17 @@ uhd::rfnoc::chdr_tx_data_xport::uptr x300_impl::x300_mb_iface::make_tx_data_tran
     send_link_if::sptr send_link;
     recv_link_if::sptr recv_link;
     bool lossy_xport;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, lossy_xport, std::ignore) =
-        _conn_mgr->get_links(link_type_t::TX_DATA,
-            local_sep_addr.first,
-            local_epid,
-            remote_epid,
-            xport_args);
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        std::ignore,
+        lossy_xport,
+        std::ignore,
+        std::ignore) = _conn_mgr->get_links(link_type_t::TX_DATA,
+        local_sep_addr.first,
+        local_epid,
+        remote_epid,
+        xport_args);
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_sep_addr.first] = send_link->get_send_adapter_id();
diff --git a/host/lib/usrp/x300/x300_pcie_mgr.cpp b/host/lib/usrp/x300/x300_pcie_mgr.cpp
index 0ca918e3c..64ce5df55 100644
--- a/host/lib/usrp/x300/x300_pcie_mgr.cpp
+++ b/host/lib/usrp/x300/x300_pcie_mgr.cpp
@@ -347,6 +347,9 @@ both_links_t pcie_manager::get_links(link_type_t link_type,
             + ", no such device associated with this motherboard!");
     }
 
+    const bool enable_fc = not link_args.has_key("enable_fc")
+                           || uhd::cast::from_str<bool>(link_args.get("enable_fc"));
+
     const uint32_t dma_channel_num = allocate_pcie_dma_chan(remote_epid, link_type);
     // Note: The nirio_link object's factory has a lot of code for sanity
     // checking the link params, and merging the link_args with the default
@@ -358,6 +361,11 @@ both_links_t pcie_manager::get_links(link_type_t link_type,
     auto link =
         nirio_link::make(_rio_fpga_interface, dma_channel_num, link_params, link_args, recv_buff_size, send_buff_size);
 
-    return std::make_tuple(
-        link, send_buff_size, link, recv_buff_size, false /*not lossy*/, false);
+    return std::make_tuple(link,
+        send_buff_size,
+        link,
+        recv_buff_size,
+        false /*not lossy*/,
+        false,
+        enable_fc);
 }