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axis_replay_buffer: Fix slave handshaking 

Handshaking happens on the rising edge based on the current values of
ready/valid. Fix the current (incorrect) logic. Additionally, modify the
testbench to properly stimulate AXI stream cores. This will catch
several handshaking failures fixed in previous commits.

Fixes: 52325f2 ("Add AXI stream replay buffer")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
This commit is contained in:
Sean Anderson 2023-03-05 14:27:56 -05:00
parent 58cebe5ac2
commit 2c2527e8d9
2 changed files with 9 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
rtl/axis_replay_buffer.v
View File

@ -62,8 +62,7 @@ module axis_replay_buffer (
parameter BUF_SIZE = 54; parameter BUF_SIZE = 54;
localparam BUF_WIDTH = $clog2(BUF_SIZE + 1); localparam BUF_WIDTH = $clog2(BUF_SIZE + 1);
reg [DATA_WIDTH - 1:0] s_axis_data_last; reg s_axis_ready_next;
reg s_axis_valid_last, s_axis_last_last, s_axis_ready_next;
reg m_axis_valid_next, m_axis_last_next; reg m_axis_valid_next, m_axis_last_next;
reg sent_last, sent_last_next; reg sent_last, sent_last_next;
reg [DATA_WIDTH - 1:0] buffer [(2 ** BUF_WIDTH) - 1:0]; reg [DATA_WIDTH - 1:0] buffer [(2 ** BUF_WIDTH) - 1:0];
@ -77,10 +76,10 @@ module axis_replay_buffer (
s_ptr_next = s_ptr; s_ptr_next = s_ptr;
last_next = last; last_next = last;
last_ptr_next = last_ptr; last_ptr_next = last_ptr;
if (s_axis_valid_last && s_axis_ready) begin if (s_axis_valid && s_axis_ready) begin
we = 1; we = 1;
s_ptr_next = s_ptr + 1; s_ptr_next = s_ptr + 1;
if (s_axis_last_last) begin if (s_axis_last) begin
last_next = 1; last_next = 1;
last_ptr_next = s_ptr; last_ptr_next = s_ptr;
end end
@ -141,11 +140,10 @@ module axis_replay_buffer (
always @(posedge clk) begin always @(posedge clk) begin
if (we) if (we)
buffer[s_ptr[BUF_WIDTH - 1:0]] <= { s_axis_data_last }; buffer[s_ptr[BUF_WIDTH - 1:0]] <= { s_axis_data };
if (re) if (re)
{ m_axis_data } <= buffer[m_ptr[BUF_WIDTH - 1:0]]; { m_axis_data } <= buffer[m_ptr[BUF_WIDTH - 1:0]];
last_ptr <= last_ptr_next; last_ptr <= last_ptr_next;
s_axis_data_last <= s_axis_data;
end end
always @(posedge clk, posedge rst) begin always @(posedge clk, posedge rst) begin
@ -154,8 +152,6 @@ module axis_replay_buffer (
s_ptr <= 0; s_ptr <= 0;
last <= 0; last <= 0;
replayable <= 1; replayable <= 1;
s_axis_valid_last <= 0;
s_axis_last_last <= 0;
s_axis_ready <= 1; s_axis_ready <= 1;
m_axis_valid <= 0; m_axis_valid <= 0;
m_axis_last <= 0; m_axis_last <= 0;
@ -165,8 +161,6 @@ module axis_replay_buffer (
s_ptr <= s_ptr_next; s_ptr <= s_ptr_next;
last <= last_next; last <= last_next;
replayable <= replayable_next; replayable <= replayable_next;
s_axis_valid_last <= s_axis_valid;
s_axis_last_last <= s_axis_last;
s_axis_ready <= s_axis_ready_next; s_axis_ready <= s_axis_ready_next;
m_axis_last <= m_axis_last_next; m_axis_last <= m_axis_last_next;
m_axis_valid <= m_axis_valid_next; m_axis_valid <= m_axis_valid_next;

11
tb/axis_replay_buffer.py
View File

@ -28,10 +28,8 @@ async def send_packet(signals, packet, ratio=1, last_extra=0):
if 'last' in signals: if 'last' in signals:
signals['last'].value = last signals['last'].value = last
await RisingEdge(signals['clk']) await RisingEdge(signals['clk'])
while True: while not signals['ready'].value:
await FallingEdge(signals['clk']) await RisingEdge(signals['clk'])
if signals['ready'].value:
break
signals['valid'].value = 0 signals['valid'].value = 0
if ratio != 1 and not last: if ratio != 1 and not last:
await ClockCycles(signals['clk'], ratio - 1, rising=False) await ClockCycles(signals['clk'], ratio - 1, rising=False)
@ -40,13 +38,14 @@ async def recv_packet(signals, packet, last=None):
if last is None: if last is None:
last = len(packet) last = len(packet)
await RisingEdge(signals['clk'])
for i, val in enumerate(packet): for i, val in enumerate(packet):
while not signals['valid'].value or not signals['ready'].value: while not signals['valid'].value or not signals['ready'].value:
await FallingEdge(signals['clk']) await RisingEdge(signals['clk'])
assert signals['data'].value == val assert signals['data'].value == val
if 'last' in signals: if 'last' in signals:
assert signals['last'].value == (i == last - 1) assert signals['last'].value == (i == last - 1)
await FallingEdge(signals['clk']) await RisingEdge(signals['clk'])
@timeout(30, 'us') @timeout(30, 'us')
async def test_replay(buf, in_ratio, out_ratio): async def test_replay(buf, in_ratio, out_ratio):