From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 16 Apr 2022 20:23:38 +0000 (+0100)
Subject: put versa_ecp5 back to synchronous at 50 mhz to test sync dram
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=45435ce4bc4d2a8946a51725c7b804c8160bc91f;p=ls2.git

put versa_ecp5 back to synchronous at 50 mhz to test sync dram
---

diff --git a/src/ls2.py b/src/ls2.py
index ec81aa3..38110d0 100644
--- a/src/ls2.py
+++ b/src/ls2.py
@@ -856,8 +856,8 @@ def build_platform(fpga, firmware):
         #dram_clk_freq = clk_freq
         dram_clk_freq = 100e6
     if fpga == 'versa_ecp5':
-        clk_freq = 40e6 # crank right down to timing threshold
-        dram_clk_freq = 55e6
+        clk_freq = 50e6 # crank right down to timing threshold
+        #dram_clk_freq = 55e6
     if fpga == 'versa_ecp5_85':
         # 50MHz works.  100MHz works.  55MHz does NOT work.
         # Stick with multiples of 50MHz...
@@ -874,6 +874,13 @@ def build_platform(fpga, firmware):
     if clk_freq == dram_clk_freq:
         dram_clk_freq = None
 
+    # see if dram can be enabled
+    enable_dram = False
+    if dram_clk_freq is not None and dram_clk_freq >= 50e6:
+        enable_dram = True
+    if dram_clk_freq is None and clk_freq >= 50e6:
+        enable_dram = True
+
     # select a firmware address
     fw_addr = None
     if firmware is not None:
@@ -894,7 +901,7 @@ def build_platform(fpga, firmware):
 
     # get DDR resource pins, disable if clock frequency is below 50 mhz for now
     ddr_pins = None
-    if (dram_clk_freq >= 50e6 and platform is not None and
+    if (enable_dram and platform is not None and
         fpga in ['versa_ecp5', 'versa_ecp5_85', 'arty_a7', 'isim']):
         ddr_pins = platform.request("ddr3", 0,
                                     dir={"dq":"-", "dqs":"-"},