Resolve HPR-131

Closes HPR-131

applications/rdma_demo/libraries/rdma_packetiser/src/vhdl/rdma_packetiser_assemble_header.vhd

@@ -45,6 +45,10 @@
 --   of messages has reached "nof_msg". Then the cycle repeats.
 -- . The PSN field (= Packet Sequence Number) is set to LSBs of the incoming BSN.
 --   This can be used to check the order or detect missing packets at the receiver.
+-- . The incoming datastream has to be at least 6 valid cycles long and be able to handle
+--   backpressure. Using less than 6 cycles seem to result in corrupted packets. It seems
+--   that it has to do with dp_offload_tx_v3 not capable of processing fast enough, further
+--   investigation is necessary in order to get rid of this limitation.
 
 -- References:
 -- . [1] https://support.astron.nl/confluence/x/3pKrB
@@ -88,8 +92,19 @@ entity rdma_packetiser_assemble_header is
 end rdma_packetiser_assemble_header;
 
 architecture str of rdma_packetiser_assemble_header is
-  constant c_udp_app_hdr_length    : natural := c_network_udp_header_len + c_rdma_packetiser_bth_len;
-  constant c_ip_udp_app_hdr_length : natural := c_network_ip_header_len + c_udp_app_hdr_length;
+  -- Created constants for each header length variant, also included the icrc length here.
+  -- first = rdma_write_first and rdma_write_only without immediate.
+  -- mid   = rdma_write_middle and rdma_write_last without immediate.
+  -- last  = rdma_write_last with immediate.
+  -- wo    = rdma_write_only with immediate.
+  constant c_udp_app_first_hdr_len    : natural := c_network_udp_header_len + c_rdma_packetiser_bth_len + c_rdma_packetiser_reth_len + c_rdma_packetiser_icrc_len;
+  constant c_udp_app_mid_hdr_len      : natural := c_network_udp_header_len + c_rdma_packetiser_bth_len + c_rdma_packetiser_icrc_len;
+  constant c_udp_app_last_hdr_len     : natural := c_network_udp_header_len + c_rdma_packetiser_bth_len + c_rdma_packetiser_imm_len  + c_rdma_packetiser_icrc_len;
+  constant c_udp_app_wo_hdr_len       : natural := c_network_udp_header_len + c_rdma_packetiser_bth_len + c_rdma_packetiser_reth_len + c_rdma_packetiser_imm_len + c_rdma_packetiser_icrc_len;
+  constant c_ip_udp_app_first_hdr_len : natural := c_network_ip_header_len + c_udp_app_first_hdr_len;
+  constant c_ip_udp_app_mid_hdr_len   : natural := c_network_ip_header_len + c_udp_app_mid_hdr_len;
+  constant c_ip_udp_app_last_hdr_len  : natural := c_network_ip_header_len + c_udp_app_last_hdr_len;
+  constant c_ip_udp_app_wo_hdr_len    : natural := c_network_ip_header_len + c_udp_app_wo_hdr_len;
   constant c_nof_offload           : natural := 4; 
 
   type t_state is (s_first, s_middle, s_last);
@@ -179,24 +194,36 @@ begin
 
           if v.nof_packets_in_msg = 1 then -- set opcode to write_only.
             v.opcode := c_rdma_packetiser_opcode_uc_write_only;
+            v.udp_total_length := c_udp_app_first_hdr_len + to_uint(block_len);
+            v.ip_total_length  := c_ip_udp_app_first_hdr_len + to_uint(block_len);
             v.sel_ctrl := 0;
             if use_immediate = '1' then  -- set opcode to write_only with immediate data.
               v.opcode := c_rdma_packetiser_opcode_uc_write_only_imm;
+              v.udp_total_length := c_udp_app_wo_hdr_len + to_uint(block_len);
+              v.ip_total_length  := c_ip_udp_app_wo_hdr_len + to_uint(block_len);
             v.sel_ctrl := 3;
             end if;
           elsif v.nof_packets_in_msg = 2 then -- set opcode to write_first.
             v.state := s_last; -- next state is last as there are only 2 packets.
             v.opcode := c_rdma_packetiser_opcode_uc_write_first;
+            v.udp_total_length := c_udp_app_first_hdr_len + to_uint(block_len);
+            v.ip_total_length  := c_ip_udp_app_first_hdr_len + to_uint(block_len);
+
             v.sel_ctrl := 0;
           elsif v.nof_packets_in_msg > 2 then
             v.state := s_middle;
             v.opcode := c_rdma_packetiser_opcode_uc_write_first;
+            v.udp_total_length := c_udp_app_first_hdr_len + to_uint(block_len);
+            v.ip_total_length  := c_ip_udp_app_first_hdr_len + to_uint(block_len);
+
             v.sel_ctrl := 0;
           end if;
 
         when s_middle => -- wait unitl the first packet is done and set next opcode.
           v.opcode := c_rdma_packetiser_opcode_uc_write_middle;
-            v.sel_ctrl := 1;
+          v.udp_total_length := c_udp_app_mid_hdr_len + to_uint(block_len);
+          v.ip_total_length  := c_ip_udp_app_mid_hdr_len + to_uint(block_len);
+          v.sel_ctrl := 1;
           if q.p_cnt >= v.nof_packets_in_msg - 2 then -- wait until last middle packet
             v.state := s_last;
           end if;
@@ -204,9 +231,13 @@ begin
         when s_last => -- next packet must be last packet, set opcode.
           v.state := s_first;
           v.opcode := c_rdma_packetiser_opcode_uc_write_last;
-            v.sel_ctrl := 1;
+          v.udp_total_length := c_udp_app_mid_hdr_len + to_uint(block_len);
+          v.ip_total_length  := c_ip_udp_app_mid_hdr_len + to_uint(block_len);
+          v.sel_ctrl := 1;
           if use_immediate = '1' then -- set opcode to write_last with immediate data
             v.opcode := c_rdma_packetiser_opcode_uc_write_last_imm;
+            v.udp_total_length := c_udp_app_last_hdr_len + to_uint(block_len);
+            v.ip_total_length  := c_ip_udp_app_last_hdr_len + to_uint(block_len);
             v.sel_ctrl := 2;
           end if;
       end case;
@@ -215,8 +246,6 @@ begin
     if v.msg_cnt = 0 then -- set on new message
       v.virtual_address    := unsigned(start_address);
       v.dma_len            := unsigned(dma_len);
-      v.udp_total_length   := c_udp_app_hdr_length    + to_uint(block_len) + c_rdma_packetiser_icrc_len;
-      v.ip_total_length    := c_ip_udp_app_hdr_length + to_uint(block_len) + c_rdma_packetiser_icrc_len;
       v.nof_packets_in_msg := to_uint(nof_packets_in_msg);
     end if;
 
@@ -278,7 +307,7 @@ begin
     hdr_fields_slv_in_first <= field_select_subset(c_rdma_packetiser_first_hdr_field_arr, 
                                                    c_rdma_packetiser_mm_field_arr, 
                                                    hdr_fields_slv_out_mm);
-    hdr_fields_slv_in_mid   <= field_select_subset(c_rdma_packetiser_last_hdr_field_arr, 
+    hdr_fields_slv_in_mid   <= field_select_subset(c_rdma_packetiser_mid_hdr_field_arr, 
                                                    c_rdma_packetiser_mm_field_arr, 
                                                    hdr_fields_slv_out_mm);
     hdr_fields_slv_in_last  <= field_select_subset(c_rdma_packetiser_last_hdr_field_arr, 

[Eric Kooistra]

why 6 ?, what does that mean in practise, is that a limitation in practise ?