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.

2 files changed, 7 insertions, 0 deletions

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);