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Step 5: Optimize stage-1 stall and stage-2 stall logic

This commit is contained in:
AngeloJacobo 2026-01-18 11:40:26 +08:00
parent f724ec0d43
commit 5066c3d280
1 changed files with 21 additions and 24 deletions
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45
rtl/ddr3_controller.v
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@ -1701,7 +1701,6 @@ module ddr3_controller #(
stage2_stall = 1'b0; stage2_stall = 1'b0;
ecc_stage2_stall = 1'b0; ecc_stage2_stall = 1'b0;
stage2_update = 1'b1; //always update stage 2 UNLESS it has a pending request (stage2_pending high) stage2_update = 1'b1; //always update stage 2 UNLESS it has a pending request (stage2_pending high)
// o_wb_stall_d = 1'b0; //wb_stall going high is determined on stage 1 (higher priority), wb_stall going low is determined at stage2 (lower priority)
precharge_slot_busy = 0; //flag that determines if stage 2 is issuing precharge (thus stage 1 cannot issue precharge) precharge_slot_busy = 0; //flag that determines if stage 2 is issuing precharge (thus stage 1 cannot issue precharge)
activate_slot_busy = 0; //flag that determines if stage 2 is issuing activate (thus stage 1 cannot issue activate) activate_slot_busy = 0; //flag that determines if stage 2 is issuing activate (thus stage 1 cannot issue activate)
write_dqs_d = write_calib_dqs; write_dqs_d = write_calib_dqs;
@ -1774,7 +1773,6 @@ module ddr3_controller #(
//USE _d in ALL //USE _d in ALL
//if there is a pending request, issue the appropriate commands //if there is a pending request, issue the appropriate commands
if(stage2_pending) begin if(stage2_pending) begin
stage2_stall = 1; //initially high when stage 2 is pending
ecc_stage2_stall = 1; ecc_stage2_stall = 1;
stage2_update = 0; stage2_update = 0;
@ -1829,7 +1827,6 @@ module ddr3_controller #(
else if(stage2_do_wr_or_rd) begin //read/write operation else if(stage2_do_wr_or_rd) begin //read/write operation
//write request //write request
if(stage2_do_wr) begin if(stage2_do_wr) begin
stage2_stall = 0;
ecc_stage2_stall = 0; ecc_stage2_stall = 0;
stage2_update = 1; stage2_update = 1;
cmd_odt = 1'b1; cmd_odt = 1'b1;
@ -1919,7 +1916,6 @@ module ddr3_controller #(
//read request //read request
else if(stage2_do_rd) begin else if(stage2_do_rd) begin
stage2_stall = 0;
ecc_stage2_stall = 0; ecc_stage2_stall = 0;
stage2_update = 1; stage2_update = 1;
cmd_odt = 1'b0; cmd_odt = 1'b0;
@ -2023,35 +2019,36 @@ module ddr3_controller #(
end //end of stage1 anticipate end //end of stage1 anticipate
end end
// control stage 1 stall // control stage 1 stall in advance
if(stage1_pending) begin //raise stall only if stage2 will still be busy next clock if(stage1_pending) begin // raise stall only if stage2 will still be busy next clock
// Stage1 bank and row will determine if transaction will be // stall stage 1 by default if there is pending request on stage 1
// stalled (bank is idle OR wrong row is active).
if(!bank_status_d[stage1_bank] || (bank_status_d[stage1_bank] && bank_active_row_d[stage1_bank] != stage1_row)) begin
stage1_stall = 1; stage1_stall = 1;
if(bank_status_d[stage1_bank] && bank_active_row_d[stage1_bank] == stage1_row) begin
// if write request and delay before write is already met then deassert stall
if(stage1_we && delay_before_write_counter_d[stage1_bank] == 0) begin
stage1_stall = 0;
end end
else if(!stage1_we && delay_before_read_counter_d[stage1_bank] != 0) begin // if read request but delay before read is not yet met then stall // if read request and delay before read is already met then deassert stall
stage1_stall = 1; else if(!stage1_we && delay_before_read_counter_d[stage1_bank] == 0) begin
stage1_stall = 0;
end end
else if(stage1_we && delay_before_write_counter_d[stage1_bank] != 0) begin // if write request but delay before write is not yet met then stall
stage1_stall = 1;
end end
//different request type will need a delay of more than 1 clk cycle so stall the pipeline
//if(stage1_we != stage2_we) begin
// stage1_stall = 1;
//end
end end
//control stage 2 stall //control stage 2 stall in advance
if(stage2_pending) begin if(stage2_pending) begin
//control stage2 stall in advance // by default, stage 2 stall deasserts once conditions for write/read command is met
if(bank_status_d[stage2_bank] && bank_active_row_d[stage2_bank] == stage2_row) begin //read/write operation stage2_stall = !(stage2_do_wr_or_rd && (stage2_do_wr || stage2_do_rd));
//write request // equivalent to: if(bank_status_d[stage2_bank] && bank_active_row_d[stage2_bank] == stage2_row)
if(stage2_we && delay_before_write_counter_d[stage2_bank] == 0) begin // if write request and delay before write is already met then deassert stall // can start read/write operation if right row is active on the bank
if(stage2_do_act || stage2_do_wr_or_rd) begin
// if write request and delay before write is already met then deassert stall
if(stage2_we && delay_before_write_counter_d[stage2_bank] == 0) begin
stage2_stall = 0; //to low stall next stage, but not yet at this stage stage2_stall = 0; //to low stall next stage, but not yet at this stage
end end
//read request // if read request and delay before read is already met then deassert stall
else if(!stage2_we && delay_before_read_counter_d[stage2_bank]==0) begin // if read request and delay before read is already met then deassert stall else if(!stage2_we && delay_before_read_counter_d[stage2_bank]==0) begin
stage2_stall = 0; stage2_stall = 0;
end end
end end