rfnoc: Fix detection of outstanding acks by ctrl_iface

There was a bug where the number of outstanding ACKS in RFNoC's
ctrl_iface was derived from the number of recv frames, which was wrong.
A number that was too low would effectively break timed commands on
tune, which would, e.g., affect phase alignment.

2 files changed, 4 insertions, 5 deletions

diff --git a/host/include/uhd/rfnoc/constants.hpp b/host/include/uhd/rfnoc/constants.hpp
index 9d9295809..53a4a01d8 100644
--- a/host/include/uhd/rfnoc/constants.hpp
+++ b/host/include/uhd/rfnoc/constants.hpp
@@ -82,7 +82,7 @@ static const uint32_t AXIS_CONFIG_BUS =
 static const uint32_t AXIS_CONFIG_BUS_TLAST =
     AXI_WRAPPER_BASE + 2; // tdata with tvalid & tlast asserted
 
-static const size_t CMD_FIFO_SIZE = 128; // Lines == multiples of 8 bytes
+static const size_t CMD_FIFO_SIZE = 256; // Lines == multiples of 8 bytes
 
 // Named settings registers
 static const uhd::dict<std::string, uint32_t> DEFAULT_NAMED_SR =
diff --git a/host/lib/rfnoc/ctrl_iface.cpp b/host/lib/rfnoc/ctrl_iface.cpp
index 0b71aebbb..6204d81f4 100644
--- a/host/lib/rfnoc/ctrl_iface.cpp
+++ b/host/lib/rfnoc/ctrl_iface.cpp
@@ -25,7 +25,7 @@ using namespace uhd;
 using namespace uhd::rfnoc;
 using namespace uhd::transport;
 
-static const double ACK_TIMEOUT = 2.0; // supposed to be worst case practical timeout
+static const double ACK_TIMEOUT     = 2.0; // supposed to be worst case practical timeout
 static const double MASSIVE_TIMEOUT = 10.0; // for when we wait on a timed command
 
 template <uhd::endianness_t _endianness> class ctrl_iface_impl : public ctrl_iface
@@ -35,9 +35,8 @@ public:
         : _xports(xports)
         , _name(name)
         , _seq_out(0)
-        , _max_outstanding_acks(std::min(
-              uhd::rfnoc::CMD_FIFO_SIZE / 3, // Max command packet size is 3 lines
-              _xports.recv->get_num_recv_frames()))
+        , _max_outstanding_acks(
+              uhd::rfnoc::CMD_FIFO_SIZE / 3) // Max command packet size is 3 lines
     {
         UHD_ASSERT_THROW(bool(_xports.send));
         UHD_ASSERT_THROW(bool(_xports.recv));