rfnoc: Update the MTU forwarding property for some blocks

Note that the default MTU forwarding policy is ONE_TO_ONE, therefore,
it is only strictly necessary to modify the MTU forwarding policy for
blocks that route data in a different manner. However, it may be nice to
explicitly state the forwarding policy for the benefit of the reader.

The following blocks had their policies updated:
- addsub: ONE_TO_FAN
- duc: ONE_TO_ONE
- dmafifo: ONE_TO_ONE
- null block: DROP
- replay block: DROP
- split stream: ONE_TO_FAN
- switchboard: ONE_TO_FAN

1 files changed, 2 insertions, 0 deletions

diff --git a/host/lib/rfnoc/ddc_block_control.cpp b/host/lib/rfnoc/ddc_block_control.cpp
index 12e89961d..fbc001cc9 100644
--- a/host/lib/rfnoc/ddc_block_control.cpp
+++ b/host/lib/rfnoc/ddc_block_control.cpp
@@ -74,6 +74,8 @@ public:
                                             << " halfbands and "
                                                "max CIC decimation "
                                             << _cic_max_decim);
+        // This line is not strictly necessary, as ONE_TO_ONE is the default.
+        // We set it make it explicit how this block works.
         set_mtu_forwarding_policy(forwarding_policy_t::ONE_TO_ONE);
         // Load list of valid decimation values
         std::set<size_t> decims{1}; // 1 is always a valid decimation