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Rework MAC TX error handling to streamline logic; pad errored frames …
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…to avoid generating runt frames

Signed-off-by: Alex Forencich <alex@alexforencich.com>
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@alexforencich
alexforencich committed Jan 30, 2024
1 parent e24f887 commit eb0f01f
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Showing 4 changed files with 203 additions and 287 deletions.
141 changes: 61 additions & 80 deletions rtl/axis_baser_tx_64.v
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Original file line number Diff line number Diff line change
Expand Up @@ -171,8 +171,8 @@ localparam [2:0]
STATE_PAD = 3'd2,
STATE_FCS_1 = 3'd3,
STATE_FCS_2 = 3'd4,
STATE_IFG = 3'd5,
STATE_WAIT_END = 3'd6;
STATE_ERR = 3'd5,
STATE_IFG = 3'd6;

reg [2:0] state_reg = STATE_IDLE, state_next;

Expand All @@ -198,6 +198,8 @@ reg [3:0] fcs_output_type_1;

reg [7:0] ifg_offset;

reg frame_reg = 1'b0, frame_next;
reg frame_error_reg = 1'b0, frame_error_next;
reg [MIN_LEN_WIDTH-1:0] frame_min_count_reg = 0, frame_min_count_next;

reg [7:0] ifg_count_reg = 8'd0, ifg_count_next;
Expand Down Expand Up @@ -353,6 +355,8 @@ always @* begin

swap_lanes_next = swap_lanes_reg;

frame_next = frame_reg;
frame_error_next = frame_error_reg;
frame_min_count_next = frame_min_count_reg;

ifg_count_next = ifg_count_reg;
Expand All @@ -376,6 +380,10 @@ always @* begin
start_packet_next = 2'b00;
error_underflow_next = 1'b0;

if (s_axis_tvalid && s_axis_tready) begin
frame_next = !s_axis_tlast;
end

if (PTP_TS_ENABLE && PTP_TS_WIDTH == 96) begin
m_axis_ptp_ts_valid_next = m_axis_ptp_ts_valid_int_reg;
m_axis_ptp_ts_adj_next[15:0] = m_axis_ptp_ts_reg[15:0];
Expand All @@ -387,6 +395,7 @@ always @* begin
case (state_reg)
STATE_IDLE: begin
// idle state - wait for data
frame_error_next = 1'b0;
frame_min_count_next = MIN_FRAME_LENGTH-4-KEEP_WIDTH;
reset_crc = 1'b1;
s_axis_tready_next = 1'b1;
Expand Down Expand Up @@ -467,44 +476,39 @@ always @* begin
s_tdata_next = s_axis_tdata_masked;
s_empty_next = keep2empty(s_axis_tkeep);

if (s_axis_tvalid) begin
if (s_axis_tlast) begin
s_axis_tready_next = 1'b0;
if (s_axis_tuser[0]) begin
output_type_next = OUTPUT_TYPE_ERROR;
ifg_count_next = 8'd8;
state_next = STATE_IFG;
if (!s_axis_tvalid || s_axis_tlast) begin
s_axis_tready_next = frame_next; // drop frame
frame_error_next = !s_axis_tvalid || s_axis_tuser[0];
error_underflow_next = !s_axis_tvalid;

if (ENABLE_PADDING && frame_min_count_reg) begin
if (frame_min_count_reg > KEEP_WIDTH) begin
s_empty_next = 0;
state_next = STATE_PAD;
end else begin
s_axis_tready_next = 1'b0;

if (ENABLE_PADDING && frame_min_count_reg) begin
if (frame_min_count_reg > KEEP_WIDTH) begin
s_empty_next = 0;
state_next = STATE_PAD;
end else begin
if (keep2empty(s_axis_tkeep) > KEEP_WIDTH-frame_min_count_reg) begin
s_empty_next = KEEP_WIDTH-frame_min_count_reg;
end
state_next = STATE_FCS_1;
end
if (keep2empty(s_axis_tkeep) > KEEP_WIDTH-frame_min_count_reg) begin
s_empty_next = KEEP_WIDTH-frame_min_count_reg;
end
if (frame_error_next) begin
state_next = STATE_ERR;
end else begin
state_next = STATE_FCS_1;
end
end
end else begin
state_next = STATE_PAYLOAD;
if (frame_error_next) begin
state_next = STATE_ERR;
end else begin
state_next = STATE_FCS_1;
end
end
end else begin
// tvalid deassert, fail frame
output_type_next = OUTPUT_TYPE_ERROR;
ifg_count_next = 8'd8;
error_underflow_next = 1'b1;
state_next = STATE_WAIT_END;
state_next = STATE_PAYLOAD;
end
end
STATE_PAD: begin
// pad frame to MIN_FRAME_LENGTH
s_axis_tready_next = 1'b0;
s_axis_tready_next = frame_next; // drop frame

output_data_next = s_tdata_reg;
output_type_next = OUTPUT_TYPE_DATA;
Expand All @@ -520,12 +524,16 @@ always @* begin
end else begin
frame_min_count_next = 0;
s_empty_next = KEEP_WIDTH-frame_min_count_reg;
state_next = STATE_FCS_1;
if (frame_error_reg) begin
state_next = STATE_ERR;
end else begin
state_next = STATE_FCS_1;
end
end
end
STATE_FCS_1: begin
// last cycle
s_axis_tready_next = 1'b0;
s_axis_tready_next = frame_next; // drop frame

output_data_next = fcs_output_data_0;
output_type_next = fcs_output_type_0;
Expand All @@ -541,7 +549,7 @@ always @* begin
end
STATE_FCS_2: begin
// last cycle
s_axis_tready_next = 1'b0;
s_axis_tready_next = frame_next; // drop frame

output_data_next = fcs_output_data_1;
output_type_next = fcs_output_type_1;
Expand Down Expand Up @@ -573,8 +581,24 @@ always @* begin
end
end
end
STATE_ERR: begin
// terminate packet with error
s_axis_tready_next = frame_next; // drop frame

output_data_next = s_tdata_reg;
output_type_next = OUTPUT_TYPE_ERROR;

ifg_count_next = 8'd12;

state_next = STATE_IFG;
end
STATE_IFG: begin
// send IFG
s_axis_tready_next = frame_next; // drop frame

output_data_next = s_tdata_reg;
output_type_next = OUTPUT_TYPE_IDLE;

if (ifg_count_reg > 8'd8) begin
ifg_count_next = ifg_count_reg - 8'd8;
end else begin
Expand All @@ -584,7 +608,7 @@ always @* begin
reset_crc = 1'b1;

if (ENABLE_DIC) begin
if (ifg_count_next > 8'd7) begin
if (ifg_count_next > 8'd7 || frame_reg) begin
state_next = STATE_IFG;
end else begin
if (ifg_count_next >= 8'd4) begin
Expand All @@ -599,7 +623,7 @@ always @* begin
state_next = STATE_IDLE;
end
end else begin
if (ifg_count_next > 8'd4) begin
if (ifg_count_next > 8'd4 || frame_reg) begin
state_next = STATE_IFG;
end else begin
s_axis_tready_next = 1'b1;
Expand All @@ -608,53 +632,6 @@ always @* begin
end
end
end
STATE_WAIT_END: begin
// wait for end of frame
s_axis_tready_next = 1'b1;

if (ifg_count_reg > 8'd4) begin
ifg_count_next = ifg_count_reg - 8'd4;
end else begin
ifg_count_next = 8'd0;
end

reset_crc = 1'b1;

if (s_axis_tvalid) begin
if (s_axis_tlast) begin
s_axis_tready_next = 1'b0;

if (ENABLE_DIC) begin
if (ifg_count_next > 8'd7) begin
state_next = STATE_IFG;
end else begin
if (ifg_count_next >= 8'd4) begin
deficit_idle_count_next = ifg_count_next - 8'd4;
swap_lanes_next = 1'b1;
end else begin
deficit_idle_count_next = ifg_count_next;
ifg_count_next = 8'd0;
swap_lanes_next = 1'b0;
end
s_axis_tready_next = 1'b1;
state_next = STATE_IDLE;
end
end else begin
if (ifg_count_next > 8'd4) begin
state_next = STATE_IFG;
end else begin
s_axis_tready_next = 1'b1;
swap_lanes_next = ifg_count_next != 0;
state_next = STATE_IDLE;
end
end
end else begin
state_next = STATE_WAIT_END;
end
end else begin
state_next = STATE_WAIT_END;
end
end
endcase
end

Expand All @@ -663,6 +640,8 @@ always @(posedge clk) begin

swap_lanes_reg <= swap_lanes_next;

frame_reg <= frame_next;
frame_error_reg <= frame_error_next;
frame_min_count_reg <= frame_min_count_next;

ifg_count_reg <= ifg_count_next;
Expand Down Expand Up @@ -788,6 +767,8 @@ always @(posedge clk) begin
if (rst) begin
state_reg <= STATE_IDLE;

frame_reg <= 1'b0;

swap_lanes_reg <= 1'b0;

ifg_count_reg <= 8'd0;
Expand Down
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