Only verify Rx latency for larger block len.

libraries/io/eth/tb/vhdl/tb_eth_tester.vhd

@@ -92,9 +92,11 @@ ARCHITECTURE tb OF tb_eth_tester IS
 
   CONSTANT c_bg_block_len_first    : NATURAL := g_bg_ctrl_first.samples_per_packet;
   CONSTANT c_bg_block_len_others   : NATURAL := g_bg_ctrl_others.samples_per_packet;
+  CONSTANT c_bg_block_len_max      : NATURAL := largest(c_bg_block_len_first, c_bg_block_len_others);
 
   CONSTANT c_bg_slot_len_first     : NATURAL := c_bg_block_len_first + g_bg_ctrl_first.gapsize;
   CONSTANT c_bg_slot_len_others    : NATURAL := c_bg_block_len_others + g_bg_ctrl_others.gapsize;
+  CONSTANT c_bg_slot_len_max       : NATURAL := largest(c_bg_slot_len_first, c_bg_slot_len_others);
 
   CONSTANT c_eth_packet_len_first  : NATURAL := func_eth_tester_eth_packet_length(c_bg_block_len_first);
   CONSTANT c_eth_packet_len_others : NATURAL := func_eth_tester_eth_packet_length(c_bg_block_len_others);
@@ -114,6 +116,7 @@ ARCHITECTURE tb OF tb_eth_tester IS
 
   -- Expected Tx --> Rx latency values obtained from a tb run
   CONSTANT c_tx_exp_latency          : NATURAL := 0;
+  CONSTANT c_rx_exp_latency_en       : BOOLEAN := c_bg_block_len_max >= 50;
   CONSTANT c_rx_exp_latency_st       : NATURAL := 27;
   CONSTANT c_rx_exp_latency_sim_tse  : NATURAL := 165;
   CONSTANT c_rx_exp_latency_tech_tse : NATURAL := 375;
@@ -482,24 +485,31 @@ BEGIN
           ASSERT rx_mon_nof_valid_arr(I) = c_mon_nof_valid_others_rx REPORT c_tb_str & "Wrong rx nof_valid for stream (" & NATURAL'IMAGE(I) & ")" SEVERITY ERROR;
         END IF;
         ASSERT tx_mon_latency_arr(I) = c_tx_exp_latency REPORT c_tb_str & "Wrong tx latency for stream (" & NATURAL'IMAGE(I) & ")" SEVERITY ERROR;
-        -- The rx_exp_latency is fixed when:
-        -- . g_loopback_eth = FALSE: the streams operate in parallel.
-        -- . g_loopback_eth = TRUE and g_nof_streams = 1, because for
-        --   g_nof_streams > 1 the streams are mulitplexed, so then the Rx
-        --   latency will vary.
-        IF g_loopback_eth = TRUE THEN
-          IF g_nof_streams = 1 THEN
-            IF g_eth_sim_level = 0 THEN
-              ASSERT almost_equal(rx_mon_latency_arr(I), c_rx_exp_latency_tech_tse, 1) REPORT
-                  c_tb_str & "Wrong rx latency using tech_tse interface" SEVERITY ERROR;
-            ELSIF g_eth_sim_level = 1 THEN
-              ASSERT almost_equal(rx_mon_latency_arr(I), c_rx_exp_latency_sim_tse, 1) REPORT
-                  c_tb_str & "Wrong rx latency using sim_tse interface" SEVERITY ERROR;
+
+        -- For short block lengths the Rx latency appears to become less, the
+        -- exact Rx latency is therefore hard to predetermine. The actual
+        -- latency is not critical, therefore it is sufficient to only very
+        -- the latency when it is more or less fixed.
+        IF c_rx_exp_latency_en THEN
+          -- The rx_exp_latency is fixed when:
+          -- . g_loopback_eth = FALSE: the streams operate in parallel.
+          -- . g_loopback_eth = TRUE and g_nof_streams = 1, because for
+          --   g_nof_streams > 1 the streams are multiplexed, so then the Rx
+          --   latency will vary.
+          IF g_loopback_eth = TRUE THEN
+            IF g_nof_streams = 1 THEN
+              IF g_eth_sim_level = 0 THEN
+                ASSERT almost_equal(rx_mon_latency_arr(I), c_rx_exp_latency_tech_tse, 1) REPORT
+                    c_tb_str & "Wrong rx latency using tech_tse interface" SEVERITY ERROR;
+              ELSIF g_eth_sim_level = 1 THEN
+                ASSERT almost_equal(rx_mon_latency_arr(I), c_rx_exp_latency_sim_tse, 1) REPORT
+                    c_tb_str & "Wrong rx latency using sim_tse interface" SEVERITY ERROR;
+              END IF;
             END IF;
+          ELSE
+            ASSERT rx_mon_latency_arr(I) = c_rx_exp_latency_st REPORT
+                c_tb_str & "Wrong rx latency using st interface (" & NATURAL'IMAGE(I) & ")" SEVERITY ERROR;
           END IF;
-        ELSE
-          ASSERT rx_mon_latency_arr(I) = c_rx_exp_latency_st REPORT
-              c_tb_str & "Wrong rx latency using st interface (" & NATURAL'IMAGE(I) & ")" SEVERITY ERROR;
         END IF;
       END IF;
     END LOOP;