rfnoc: Add option to disable flow control on rx streaming

Disabling this feature will allow the USRP to send a continuous stream
of Rx data to a host machine without throttling due to lack of flow
control credits. This is unnecessary overhead on lossless transports
such as pcie or aurora.

Usage: add 'enable_fc=false' to stream_args.args

Signed-off-by: mattprost <matt.prost@ni.com>

9 files changed, 146 insertions, 60 deletions

diff --git a/host/lib/include/uhdlib/rfnoc/mgmt_portal.hpp b/host/lib/include/uhdlib/rfnoc/mgmt_portal.hpp
index afe438140..0e3e887f3 100644
--- a/host/lib/include/uhdlib/rfnoc/mgmt_portal.hpp
+++ b/host/lib/include/uhdlib/rfnoc/mgmt_portal.hpp
@@ -148,9 +148,13 @@ public:
     //
     // \param xport The host stream endpoint's CTRL transport (same EPID as RX stream)
     // \param epid The endpoint ID of the data source
+    // \param timeout The max time to wait on stream validation
+    // \param fc_enabled Enable flow control in the FPGA
     //
-    virtual stream_buff_params_t config_local_rx_stream_commit(
-        chdr_ctrl_xport& xport, const sep_id_t& epid, const double timeout = 0.2) = 0;
+    virtual stream_buff_params_t config_local_rx_stream_commit(chdr_ctrl_xport& xport,
+        const sep_id_t& epid,
+        const double timeout  = 0.2,
+        const bool fc_enabled = true) = 0;
 
     //! Configure a flow controlled transmit data stream from this SW mgmt portal to the
     //  endpoint with the specified ID.
@@ -177,6 +181,8 @@ public:
     // \param mdata_buff_fmt Datatype of SW buffer that holds the data metadata
     // \param fc_freq Flow control response frequency parameters
     // \param fc_freq Flow control headroom parameters
+    // \param reset Reset source and destination stream endpoint states
+    // \param timeout The max time to wait on stream validation
     //
     virtual stream_buff_params_t config_remote_stream(chdr_ctrl_xport& xport,
         const sep_id_t& dst_epid,
diff --git a/host/lib/include/uhdlib/transport/links.hpp b/host/lib/include/uhdlib/transport/links.hpp
index f9d08de11..89d5774ce 100644
--- a/host/lib/include/uhdlib/transport/links.hpp
+++ b/host/lib/include/uhdlib/transport/links.hpp
@@ -20,7 +20,8 @@ using both_links_t = std::tuple<uhd::transport::send_link_if::sptr,
     uhd::transport::recv_link_if::sptr,
     size_t, // num_recv_frames
     bool, // lossy_xport
-    bool>; // packet flow control
+    bool, // packet flow control
+    bool>; // enable flow control
 
 /*!
  * Parameters for link creation.
diff --git a/host/lib/rfnoc/chdr_rx_data_xport.cpp b/host/lib/rfnoc/chdr_rx_data_xport.cpp
index 74b310fa1..7089c9071 100644
--- a/host/lib/rfnoc/chdr_rx_data_xport.cpp
+++ b/host/lib/rfnoc/chdr_rx_data_xport.cpp
@@ -200,7 +200,9 @@ chdr_rx_data_xport::fc_params_t chdr_rx_data_xport::configure_sep(io_service::sp
     recv_io->release_recv_buff(std::move(buff));
 
     // Finally, let the management portal know the setup is complete
-    mgmt_portal.config_local_rx_stream_commit(*ctrl_xport, remote_epid);
+    const bool fc_enabled = (fc_freq.bytes != 0) || (fc_freq.packets != 0);
+    mgmt_portal.config_local_rx_stream_commit(
+        *ctrl_xport, remote_epid, 0.2 /*default timeout*/, fc_enabled);
 
     // The flow control frequency requested is contained in the strc
     UHD_LOG_TRACE("XPORT::RX_DATA_XPORT",
diff --git a/host/lib/rfnoc/mgmt_portal.cpp b/host/lib/rfnoc/mgmt_portal.cpp
index 0ebc9654d..2b843ae03 100644
--- a/host/lib/rfnoc/mgmt_portal.cpp
+++ b/host/lib/rfnoc/mgmt_portal.cpp
@@ -503,14 +503,16 @@ public:
             (boost::format("Initiated RX stream setup for EPID=%d") % epid));
     }
 
-    stream_buff_params_t config_local_rx_stream_commit(
-        chdr_ctrl_xport& xport, const sep_id_t& epid, const double timeout = 0.2) override
+    stream_buff_params_t config_local_rx_stream_commit(chdr_ctrl_xport& xport,
+        const sep_id_t& epid,
+        const double timeout  = 0.2,
+        const bool fc_enabled = true) override
     {
         std::lock_guard<std::recursive_mutex> lock(_mutex);
 
         // Wait for stream configuration to finish on the HW side
         const node_addr_t& node_addr = _lookup_sep_node_addr(epid);
-        _validate_stream_setup(xport, node_addr, timeout);
+        _validate_stream_setup(xport, node_addr, timeout, fc_enabled);
 
         UHD_LOG_DEBUG("RFNOC::MGMT",
             (boost::format("Finished RX stream setup for EPID=%d") % epid));
@@ -574,6 +576,7 @@ public:
     {
         std::lock_guard<std::recursive_mutex> lock(_mutex);
         auto my_epid = xport.get_epid();
+        const bool fc_enabled = (fc_freq.bytes != 0) || (fc_freq.packets != 0);
 
         // First setup a route between the two endpoints
         setup_remote_route(xport, dst_epid, src_epid);
@@ -638,7 +641,7 @@ public:
         }
 
         // Wait for stream configuration to finish on the HW side
-        _validate_stream_setup(xport, src_node_addr, timeout);
+        _validate_stream_setup(xport, src_node_addr, timeout, fc_enabled);
 
         UHD_LOG_DEBUG("RFNOC::MGMT",
             (boost::format("Setup a stream from EPID=%d to EPID=%d") % src_epid
@@ -931,8 +934,10 @@ private: // Functions
     }
 
     // Make sure that stream setup is complete and successful, else throw exception
-    void _validate_stream_setup(
-        chdr_ctrl_xport& xport, const node_addr_t& node_addr, const double timeout)
+    void _validate_stream_setup(chdr_ctrl_xport& xport,
+        const node_addr_t& node_addr,
+        const double timeout,
+        const bool fc_enabled)
     {
         // Get the status of the output stream
         uint32_t ostrm_status = 0;
@@ -954,7 +959,7 @@ private: // Functions
         if ((ostrm_status & STRM_STATUS_SETUP_ERR) != 0) {
             throw uhd::op_failed("config_stream: Setup failure");
         }
-        if ((ostrm_status & STRM_STATUS_FC_ENABLED) == 0) {
+        if (fc_enabled != bool(ostrm_status & STRM_STATUS_FC_ENABLED)) {
             throw uhd::op_failed("config_stream: Flow control negotiation failed");
         }
     }
diff --git a/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp b/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp
index d5be57cd9..6fc36bf72 100644
--- a/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp
+++ b/host/lib/usrp/mpmd/mpmd_link_if_ctrl_udp.cpp
@@ -12,6 +12,7 @@
 #include <uhd/transport/udp_constants.hpp>
 #include <uhd/transport/udp_simple.hpp>
 #include <uhd/transport/udp_zero_copy.hpp>
+#include <uhd/utils/cast.hpp>
 #include <uhdlib/rfnoc/rfnoc_common.hpp>
 #include <uhdlib/transport/udp_boost_asio_link.hpp>
 #include <uhdlib/transport/udp_common.hpp>
@@ -283,6 +284,9 @@ uhd::transport::both_links_t mpmd_link_if_ctrl_udp::get_link(const size_t link_i
     const std::string udp_port = _udp_info.at(ip_addr).udp_port;
 
     const size_t link_rate = get_link_rate(link_idx);
+    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 bool use_dpdk = _mb_args.has_key("use_dpdk");  // FIXME use constrained device args
     link_params_t default_link_params;
     default_link_params.num_send_frames = MPMD_ETH_NUM_FRAMES;
@@ -327,8 +331,9 @@ uhd::transport::both_links_t mpmd_link_if_ctrl_udp::get_link(const size_t link_i
             link_params.send_buff_size,
             link,
             link_params.recv_buff_size,
+            lossy_xport,
             true,
-            true);
+            enable_fc);
 #else
         UHD_LOG_WARNING("MPMD", "Cannot create DPDK transport, falling back to UDP");
 #endif
@@ -338,8 +343,13 @@ uhd::transport::both_links_t mpmd_link_if_ctrl_udp::get_link(const size_t link_i
         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);
 }
 
 size_t mpmd_link_if_ctrl_udp::get_num_links() const
diff --git a/host/lib/usrp/mpmd/mpmd_mb_iface.cpp b/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
index a24be5c57..70e982fc7 100644
--- a/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
+++ b/host/lib/usrp/mpmd/mpmd_mb_iface.cpp
@@ -165,9 +165,15 @@ uhd::rfnoc::chdr_ctrl_xport::sptr mpmd_mboard_impl::mpmd_mb_iface::make_ctrl_tra
     const size_t link_idx = _local_device_id_map.at(local_device_id);
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, std::ignore, std::ignore) =
-        _link_if_mgr->get_link(
-            link_idx, uhd::transport::link_type_t::CTRL, uhd::device_addr_t());
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        std::ignore,
+        std::ignore,
+        std::ignore,
+        std::ignore) = _link_if_mgr->get_link(link_idx,
+        uhd::transport::link_type_t::CTRL,
+        uhd::device_addr_t());
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_device_id] = send_link->get_send_adapter_id();
@@ -211,11 +217,17 @@ mpmd_mboard_impl::mpmd_mb_iface::make_rx_data_transport(
 
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
-    bool lossy_xport, packet_fc;
+    bool lossy_xport, packet_fc, enable_fc;
     size_t recv_buff_size;
-    std::tie(send_link, std::ignore, recv_link, recv_buff_size, lossy_xport, packet_fc) =
-        _link_if_mgr->get_link(
-            link_idx, uhd::transport::link_type_t::RX_DATA, xport_args);
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        recv_buff_size,
+        lossy_xport,
+        packet_fc,
+        enable_fc) = _link_if_mgr->get_link(link_idx,
+        uhd::transport::link_type_t::RX_DATA,
+        xport_args);
 
     /* Associate local device ID with the adapter */
     _adapter_map[local_sep_addr.first] = send_link->get_send_adapter_id();
@@ -226,14 +238,19 @@ mpmd_mboard_impl::mpmd_mb_iface::make_rx_data_transport(
 
     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};
     }
 
     stream_buff_params_t fc_headroom = {0, 0};
@@ -306,9 +323,15 @@ mpmd_mboard_impl::mpmd_mb_iface::make_tx_data_transport(
     uhd::transport::send_link_if::sptr send_link;
     uhd::transport::recv_link_if::sptr recv_link;
     bool lossy_xport;
-    std::tie(send_link, std::ignore, recv_link, std::ignore, lossy_xport, std::ignore) =
-        _link_if_mgr->get_link(
-            link_idx, uhd::transport::link_type_t::TX_DATA, xport_args);
+    std::tie(send_link,
+        std::ignore,
+        recv_link,
+        std::ignore,
+        lossy_xport,
+        std::ignore,
+        std::ignore) = _link_if_mgr->get_link(link_idx,
+        uhd::transport::link_type_t::TX_DATA,
+        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_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);
 }