From 9bc052de8b2718d435add0ee0657814ab5c5799f Mon Sep 17 00:00:00 2001
From: Alex Forencich <alex@alexforencich.com>
Date: Wed, 26 Jul 2023 14:53:01 -0700
Subject: [PATCH] Another update to async FIFO timing constraints to deal with
 OOC clock constraints

Signed-off-by: Alex Forencich <alex@alexforencich.com>
---
 syn/vivado/axis_async_fifo.tcl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/syn/vivado/axis_async_fifo.tcl b/syn/vivado/axis_async_fifo.tcl
index 817ac33bb..46a1cce77 100644
--- a/syn/vivado/axis_async_fifo.tcl
+++ b/syn/vivado/axis_async_fifo.tcl
@@ -86,7 +86,9 @@ foreach fifo_inst [get_cells -hier -filter {(ORIG_REF_NAME == axis_async_fifo ||
     set output_reg_ffs [get_cells -quiet "$fifo_inst/m_axis_pipe_reg_reg[0][*]"]
 
     if {[llength $output_reg_ffs]} {
-        set_false_path -from $write_clk -to $output_reg_ffs
+        if {[llength $write_clk]} {
+            set_false_path -from $write_clk -to $output_reg_ffs
+        }
     }
 
     # frame FIFO pointer update synchronization