Improved description.

libraries/technology/mac_10g/tech_mac_10g.vhd

@@ -23,12 +23,38 @@
 
 -- Purpose:
 -- Description:
--- Remarks:
--- . If g_pre_header_padding is TRUE then remove pre header padding from ST tx
+--
+--   If g_pre_header_padding is TRUE then remove pre header padding from ST tx
 --   and insert it in ST rx, because the 10G MAC IP does not use pre header
 --   padding. When g_pre_header_padding is FALSE then the ST frame is directly
---   passed on.
-
+--   passed on via the dp_latency_adapters. The dp_latency_adapters are needed
+--   because the ST interface uses RL=1 whereas e.g. the Altera mac_10g IP uses
+--   RL=0.
+--
+--                                            tx_remove_snk      tx_mac_snk
+--              __________                     .  ______________  .  __________________
+--              |        |                     .  |            |  .  |                |
+--              | dp_pad |                     .  | dp_latency |  .  |                |
+--    tx_snk -->| remove |----------------------->| adapter    |---->|                |
+--              |        |                        | RL=1 --> 0 |     |                |
+--              |________|                        |____________|     |                |
+--                                                                   |tech_mac_10g    |
+--              __________     ______________     ______________     |ip_<device_name>|---XGMII
+--              |        |     |            |     |            |     |                |
+--              | dp_pad |     | dp_latency |     | dp_latency |     |                |
+--    rx_src <--| insert |<----| fifo       |<----| adapter    |<----|                |
+--              |        |  .  |            |  .  | RL=1 --> 0 |  .  |                |
+--              |________|  .  |____________|  .  |____________|  .  |________________|
+--                          .                  .                  .           |
+--                          x_fifo_src        rx_mac_src_rl1     rx_mac_src   |
+--                                                                            |
+--                                                                           csr
+--
+-- Remarks:
+-- . The dp_latency_fifo is necessary because the rx_mac_src_in.ready must remain
+--   active during a reception, otherwise the rx frame gets truncated due to
+--   back pressure by dp_pad_insert.
+--
 
 LIBRARY IEEE, common_lib, dp_lib, technology_lib;
 USE IEEE.STD_LOGIC_1164.ALL;