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[rtl] Add reset to lockstep delayed inputs

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In tests with multiple resets, these signals could hold onto spurious
values through reset (since the clock is also gated) which caused
assertion failures on resumption.

Fixes #1368

Signed-off-by: Tom Roberts <tomroberts@lowrisc.org>
This commit is contained in:
Tom Roberts 2021-06-17 15:14:08 +01:00 • committed by Tom Roberts
parent 2ce6653c65
commit f3b163af35
1 changed files with 16 additions and 8 deletions
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24
rtl/ibex_lockstep.sv
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@ -170,15 +170,23 @@ module ibex_lockstep import ibex_pkg::*; #(
assign shadow_inputs_in.debug_req = debug_req_i;
// Delay the inputs
always_ff @(posedge clk_i) begin
for (int unsigned i = 0; i < LockstepOffset-1; i++) begin
shadow_inputs_q[i] <= shadow_inputs_q[i+1];
shadow_tag_rdata_q[i] <= shadow_tag_rdata_q[i+1];
shadow_data_rdata_q[i] <= shadow_data_rdata_q[i+1];
always_ff @(posedge clk_i or negedge rst_ni) begin
if (!rst_ni) begin
for (int unsigned i = 0; i < LockstepOffset; i++) begin
shadow_inputs_q[i] <= delayed_inputs_t'('0);
shadow_tag_rdata_q[i] <= '{default:0};
shadow_data_rdata_q[i] <= '{default:0};
end
end else begin
for (int unsigned i = 0; i < LockstepOffset-1; i++) begin
shadow_inputs_q[i] <= shadow_inputs_q[i+1];
shadow_tag_rdata_q[i] <= shadow_tag_rdata_q[i+1];
shadow_data_rdata_q[i] <= shadow_data_rdata_q[i+1];
end
shadow_inputs_q[LockstepOffset-1] <= shadow_inputs_in;
shadow_tag_rdata_q[LockstepOffset-1] <= ic_tag_rdata_i;
shadow_data_rdata_q[LockstepOffset-1] <= ic_data_rdata_i;
end
shadow_inputs_q[LockstepOffset-1] <= shadow_inputs_in;
shadow_tag_rdata_q[LockstepOffset-1] <= ic_tag_rdata_i;
shadow_data_rdata_q[LockstepOffset-1] <= ic_data_rdata_i;
end
///////////////////