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, 4 insertions, 0 deletions

diff --git a/host/lib/rfnoc/switchboard_block_control.cpp b/host/lib/rfnoc/switchboard_block_control.cpp
index eec7f666f..b577d510d 100644
--- a/host/lib/rfnoc/switchboard_block_control.cpp
+++ b/host/lib/rfnoc/switchboard_block_control.cpp
@@ -36,6 +36,10 @@ public:
         // Configure property propagation and action forwarding behavior.
         set_prop_forwarding_policy(forwarding_policy_t::USE_MAP);
         set_action_forwarding_policy(forwarding_policy_t::USE_MAP);
+        // MTU forwarding doesn't allow for USE_MAP, but we assume that packets
+        // coming in may potentially go to any output port. We thus fan out the
+        // MTU propagation.
+        set_mtu_forwarding_policy(forwarding_policy_t::ONE_TO_FAN);
 
         _update_forwarding_map();
     }