Can RGMII IP be used for Xilinx UltraScale technology?

1

Hi, has anyone used the RGMII IP to adapt GMII/RGMII?

In GRLIB, the ‘RGMII’ uses IDDR and ODDR primitives, but it seems that the ‘unisim_oddd_reg’ entity does not have support for Xilinx UltraScale technology.

How should I handle this, or are there any other solutions that support RGMII for GRETH ?

2

I made a small tech patch, now, it is working.

--- grlib-gpl-2024.4-b4295\lib\techmap\unisim\ddr_unisim.vhd.bak      2024-12-23 20:57:56.661136800 +0800
+++ grlib-gpl-2024.4-b4295\lib\techmap\unisim\ddr_unisim.vhd  2025-02-01 00:23:27.915784200 +0800
@@ -106,7 +106,7 @@

 begin
     KU : if (tech = kintexu) or (tech = virtexup) generate
-           U0 : IDDRE1 generic map( IS_CB_INVERTED => '1')
+           U0 : IDDRE1 generic map( IS_CB_INVERTED => '0')
                    Port map(Q1 => Q1, Q2 => Q2, C => C1, CB => C1, D => D, R => R);
     end generate;

@@ -328,6 +328,22 @@
 architecture rtl of unisim_oddr_reg is
   attribute BOX_TYPE : string;

+  component ODDRE1
+  generic (
+    IS_C_INVERTED  : bit    := '0';  -- Optional inversion for C
+    IS_D1_INVERTED : bit    := '0';  -- Unsupported, do not use
+    IS_D2_INVERTED : bit    := '0';  -- Unsupported, do not use
+    SIM_DEVICE : string := "ULTRASCALE_PLUS"; -- Set the device version for simulation functionality (ULTRASCALE,
+                                     -- ULTRASCALE_PLUS, ULTRASCALE_PLUS_ES1, ULTRASCALE_PLUS_ES2)
+    SRVAL : bit    := '0');          -- Initializes the ODDRE1 Flip-Flops to the specified value ('0', '1')
+  port (
+    Q  : out std_logic;
+    C  : in  std_logic;
+    D1 : in  std_logic;
+    D2 : in  std_logic;
+    SR : in  std_logic);
+  end component;
+  attribute BOX_TYPE of ODDRE1 : component is "PRIMITIVE";

   component ODDR
     generic
@@ -391,6 +407,11 @@

 begin

+  KU : if (tech = kintexu) or (tech = virtexup) generate
+    U0 : ODDRE1 generic map(SRVAL => '0', IS_C_INVERTED  => '0', IS_D1_INVERTED => '0', IS_D2_INVERTED => '0', SIM_DEVICE => "ULTRASCALE_PLUS")
+    port map(Q => Q, C => C1, D1 => D1, D2 => D2, SR => R);
+  end generate;
+
   V7 : if (tech = virtex7) or (tech = kintex7) or (tech = artix7) generate
      U0 : ODDR generic map( DDR_CLK_EDGE => "SAME_EDGE")
        port map(
3

Hi WEI,

Thanks for the patch! I will look into adding this to the Ultrascale techmap implementation. I’d say your change looks good though, but we need to test this on our side to be able to confirm it.

Regards,
Joaquin

4

Hi WEI,

This has now been integrated in GRLIB and will be part of the June release. Your suggestion to include the missing ODDRE1 component for Ultrascale was definitely correct and is now in place. However, changing the generic IS_CB_INVERTED in IDDRE1 from ‘1’ to ‘0’ was not included. In our tests, that would mean that only ‘even’ data are sampled (and twice, Q2 = Q1 shifted). Did you fully validate this change on your side?

Regards,
Joaquin

5

I don’t quite remember the considerations at that time, it works on real hardware, but it has not been fully confirmed through stress testing and EDA simulation.

Actually, I removed the change to IDDRE1 later.