Fix reset CDC in AXI VFIFO

Signed-off-by: Alex Forencich <[email protected]>
alexforencich · Mar 30, 2023 · 38915fb · 38915fb
1 parent 59d37ee
commit 38915fb
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/rtl/axi_vfifo.v b/rtl/axi_vfifo.v
@@ -415,10 +415,14 @@ for (n = 0; n < AXI_CH; n = n + 1) begin : axi_ch
     // control sync
     (* shreg_extract = "no" *)
     reg ch_cfg_enable_sync_1_reg = 1'b0,  ch_cfg_enable_sync_2_reg = 1'b0;
+    (* shreg_extract = "no" *)
+    reg ch_cfg_reset_sync_1_reg = 1'b0,  ch_cfg_reset_sync_2_reg = 1'b0;
 
     always @(posedge ch_clk) begin
         ch_cfg_enable_sync_1_reg <= cfg_enable_reg;
         ch_cfg_enable_sync_2_reg <= ch_cfg_enable_sync_1_reg;
+        ch_cfg_reset_sync_1_reg <= cfg_reset_reg;
+        ch_cfg_reset_sync_2_reg <= ch_cfg_reset_sync_1_reg;
     end
 
     // status sync
@@ -535,7 +539,7 @@ for (n = 0; n < AXI_CH; n = n + 1) begin : axi_ch
         .cfg_fifo_base_addr(cfg_fifo_base_addr_reg[AXI_ADDR_WIDTH*n +: AXI_ADDR_WIDTH]),
         .cfg_fifo_size_mask(cfg_fifo_size_mask_reg),
         .cfg_enable(ch_cfg_enable_sync_2_reg),
-        .cfg_reset(cfg_reset_reg),
+        .cfg_reset(ch_cfg_reset_sync_2_reg),
 
         /*
          * Status

diff --git a/syn/vivado/axi_vfifo.tcl b/syn/vivado/axi_vfifo.tcl
@@ -49,6 +49,7 @@ foreach inst [get_cells -hier -filter {(ORIG_REF_NAME == axi_vfifo || REF_NAME =
 
     # control
     constrain_sync_chain $inst "cfg_enable_reg_reg" "axi_ch[*].ch_cfg_enable_sync_1_reg_reg" "axi_ch[*].ch_cfg_enable_sync_2_reg_reg"
+    constrain_sync_chain $inst "cfg_reset_reg_reg" "axi_ch[*].ch_cfg_reset_sync_1_reg_reg" "axi_ch[*].ch_cfg_reset_sync_2_reg_reg"
 
     set sync_ffs [get_cells "$inst/cfg_fifo_base_addr_reg_reg[*] $inst/axi_ch[*].axi_vfifo_raw_inst/fifo_base_addr_reg_reg[*]"]