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descrambler: Break up locking logic 

This (un)locking logic was on the critical path. Break it up into
multiple parts to allow achieving our desired clock frequency.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
This commit is contained in:
Sean Anderson 2022-10-16 17:27:08 -04:00
parent 42c1e93338
commit 67cf4100c6
1 changed files with 12 additions and 4 deletions
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16
rtl/descramble.v
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@ -13,7 +13,8 @@ module descramble (
output reg [1:0] unscrambled, unscrambled_valid
);
reg locked_next;
reg relock, relock_next, locked_next;
initial relock = 0;
reg [1:0] ldd, unscrambled_next;
reg [10:0] lfsr, lfsr_next;
@ -73,15 +74,20 @@ module descramble (
idle_counter_next = CONSECUTIVE_IDLES;
end
locked_next = 1;
unlock_counter_next = unlock_counter;
relock_next = 0;
if (!idle_counter_next[4:1]) begin
unlock_counter_next = test_mode ? TEST_UNLOCK_TIME : UNLOCK_TIME;
/*
* Reset the counter to 2 to ensure we can always
* subtract idles without underflowing
*/
idle_counter_next = 2;
relock_next = 1;
end
locked_next = 1;
unlock_counter_next = unlock_counter;
if (relock) begin
unlock_counter_next = test_mode ? TEST_UNLOCK_TIME : UNLOCK_TIME;
end else if (|unlock_counter) begin
unlock_counter_next = unlock_counter - 1;
end else begin
@ -94,12 +100,14 @@ module descramble (
if (signal_status) begin
lfsr <= lfsr_next;
idle_counter <= idle_counter_next;
relock <= relock_next;
unlock_counter <= unlock_counter_next;
locked <= locked_next;
unscrambled_valid <= scrambled_valid;
end else begin
lfsr <= 0;
idle_counter <= CONSECUTIVE_IDLES;
relock <= 0;
unlock_counter <= 0;
locked <= 0;
unscrambled_valid <= 0;