Fix handshake in burst manager

Author: mbertuletti

rtl/variable_latency_interconnect/burst_manager.sv

@@ -90,15 +90,13 @@ module burst_manager
   arb_data_t                   postarb_data;
   logic                        postarb_valid, postarb_ready;
   logic      [NumOutLog2-1:0]  postarb_idx;
-  logic      [NumOut-1:0]  ready_mask;
-  logic      [NumOut-1:0]  valid_mask;
+  logic      [NumOut-1:0]      ready_mask;
+  logic      [NumOut-1:0]      valid_mask;
 
   always_comb begin
     prearb_data    = '0;
     prearb_valid   = '0;
     valid_mask     = req_valid_i;
-    ready_mask     = '0;
-
     for (int unsigned i = 0; i < NumOut; i++) begin
       if (req_valid_i[i] && req_burst_i[i].isburst) begin
         prearb_data[i].ini_addr = req_ini_addr_i[i];
@@ -109,10 +107,6 @@ module burst_manager
         prearb_data[i].burst = req_burst_i[i];
         prearb_valid[i] = 1'b1;
         valid_mask[i] = 1'b0;
-        // Mark retired burst requests
-        if (prearb_ready[i]) begin
-          ready_mask[i]   = 1'b1;
-        end
       end
     end
   end
@@ -165,7 +159,7 @@ module burst_manager
   // Fall though FIFO to store bursts
   fifo_v3 #(
     .FALL_THROUGH ( 1'b1            ),
-    .DEPTH        ( NumOut         ),
+    .DEPTH        ( NumOut          ),
     .dtype        ( fifo_data_t     )
   ) i_fall_though_fifo (
     .clk_i        ( clk_i           ),
@@ -206,9 +200,6 @@ module burst_manager
   `FF(burst_mask_q, burst_mask_d, '0, clk_i, rst_ni);
   `FF(group_mask_q, group_mask_d, '0, clk_i, rst_ni);
 
-  // Block burstlen ports after the port receiving a burst
-  assign req_ready_o = ready_mask | (req_ready_i & ~burst_mask_q);
-
   always_comb begin : request_generator
 
     // FSM defaults
@@ -227,16 +218,21 @@ module burst_manager
     req_ini_addr_o = req_ini_addr_i;
     req_wen_o = req_wen_i;
     req_be_o = req_be_i;
+
     // Let valid requests not in burst pass
-    req_valid_o = valid_mask;
+    req_valid_o = valid_mask & ~burst_mask_q;
+    // Send ready for valid request not in burst and for retired bursts
+    ready_mask = prearb_valid & prearb_ready;
+    req_ready_o = ((req_ready_i & valid_mask) & ~burst_mask_q) | ready_mask;
 
     case (state_q)
 
       // Idle state, ready to take in burst request
       Idle: begin
 
-        // Clear mask (unlock banks)
         burst_mask_d  = '0;
+
+        // Start pending burst
         if (~fifo_empty) begin
           // there is pending burst request
           // start to handling the burst, mark as not ready
@@ -257,6 +253,7 @@ module burst_manager
 
         // Check if there is pending responses among the affected banks
         pending_rsp = |((resp_valid_o & ~resp_ready_i) & burst_mask_q);
+
         // If no pending response and all the affected banks are ready send a new request
         if (&(req_ready_i | (~burst_mask_q)) && !pending_rsp) begin
           for (int unsigned i = 0; i < NumOut; i++) begin
@@ -271,6 +268,8 @@ module burst_manager
               req_valid_o[i] = 1'b1;
             end
           end
+          // Clear mask (unlock banks)
+          burst_mask_d = '0;
           // Switch state
           state_d = Idle;
         end