From 0c0689f444f285550304c21ac463a2ab0fd64e67 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Mon, 22 Jun 2020 13:37:14 +0200
Subject: [PATCH] wishbone/DownConverter: fix read datapath when access is
 skipped because sel = 0.

We also need to shift dat_r when acess is skipped.
---
 litex/soc/interconnect/wishbone.py | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/litex/soc/interconnect/wishbone.py b/litex/soc/interconnect/wishbone.py
index 9b45ce553..6b36e1b90 100644
--- a/litex/soc/interconnect/wishbone.py
+++ b/litex/soc/interconnect/wishbone.py
@@ -235,6 +235,7 @@ class DownConverter(Module):
 
         # # #
 
+        skip    = Signal()
         counter = Signal(max=ratio)
 
         # Control Path
@@ -252,12 +253,11 @@ class DownConverter(Module):
             slave.adr.eq(Cat(counter, master.adr)),
             Case(counter, {i: slave.sel.eq(master.sel[i*dw_to//8:]) for i in range(ratio)}),
             If(master.stb & master.cyc,
-                If(slave.sel != 0,
-                    slave.we.eq(master.we),
-                    slave.cyc.eq(1),
-                    slave.stb.eq(1),
-                ),
-                If(slave.ack | (slave.sel == 0),
+                skip.eq(slave.sel == 0),
+                slave.we.eq(master.we),
+                slave.cyc.eq(~skip),
+                slave.stb.eq(~skip),
+                If(slave.ack | skip,
                     NextValue(counter, counter + 1),
                     If(counter == (ratio - 1),
                         master.ack.eq(1),
@@ -273,7 +273,7 @@ class DownConverter(Module):
         # Read Datapath
         dat_r = Signal(dw_from, reset_less=True)
         self.comb += master.dat_r.eq(Cat(dat_r[dw_to:], slave.dat_r))
-        self.sync += If(slave.ack, dat_r.eq(master.dat_r))
+        self.sync += If(slave.ack | skip, dat_r.eq(master.dat_r))
 
 
 class Converter(Module):