rfnoc: replay block: Disable prop and action propagation

The replay block is more like the radio block than like a FIFO. In
particular, consider this flow graph:

    Replay -> DDC -> Replay

Imagine you're using the replay block to test the DDC block with
prerecorded data. If we treated the Replay Block like a FIFO, then we'd
have a loop in the graph (which is already wrong). If we used the DDC to
resample, then the input- and output sample rate of the Replay mismatch,
which is a legal way to use the Replay block, but not possible if we
treat the graph like a loop.

1 files changed, 10 insertions, 1 deletions

diff --git a/host/lib/rfnoc/replay_block_control.cpp b/host/lib/rfnoc/replay_block_control.cpp
index 201390cd1..e2d2523da 100644
--- a/host/lib/rfnoc/replay_block_control.cpp
+++ b/host/lib/rfnoc/replay_block_control.cpp
@@ -79,7 +79,11 @@ public:
             uint16_t((_replay_reg_iface.peek32(REG_MEM_SIZE_ADDR) >> 16) & 0xFFFF) / 8),
         _mem_size(uint64_t(1ULL << (_replay_reg_iface.peek32(REG_MEM_SIZE_ADDR) & 0xFFFF)))
     {
-        UHD_ASSERT_THROW(get_num_input_ports() == get_num_output_ports());
+        if (get_num_input_ports() != get_num_output_ports()) {
+            throw uhd::assertion_error(
+                "Replay block has invalid hardware configuration! Number of input ports "
+                "does not match number of output ports.");
+        }
         uhd::assert_fpga_compat(MAJOR_COMPAT,
             MINOR_COMPAT,
             _fpga_compat,
@@ -87,6 +91,11 @@ public:
             get_unique_id(),
             false /* Let it slide if minors mismatch */
         );
+        // Properties and actions can't propagate through this block, as we
+        // treat source and sink of this block like the radio (they terminate
+        // the graph).
+        set_prop_forwarding_policy(forwarding_policy_t::DROP);
+        set_action_forwarding_policy(forwarding_policy_t::DROP);
 
         // Initialize record properties
         _record_type.reserve(_num_input_ports);