Merge pull request pulp-platform#27 from planvtech/PROJ-271-amo-lr-reservation-erroneously-cleared-by-writeback

Wait for completion on write back before AMO

Author: maxbjurling

core/cache_subsystem/miss_handler.sv

@@ -102,7 +102,8 @@ module miss_handler import ariane_pkg::*; import std_cache_pkg::*; #(
         WB_CACHELINE_AMO,   // F
         AMO_WAIT_RESP,      // 10
         SEND_CLEAN,         // 11
-        REQ_CACHELINE_UNIQUE // 12
+        REQ_CACHELINE_UNIQUE, // 12
+        WB_CACHELINE_AMO_WAIT_ACK // 13
     } state_d, state_q;
 
     // Registers
@@ -432,11 +433,19 @@ module miss_handler import ariane_pkg::*; import std_cache_pkg::*; #(
                     state_d = (state_q == WB_CACHELINE_MISS) ?
                                 (colliding_clean_q[mshr_q.id] ? REQ_CACHELINE_UNIQUE : REQ_CACHELINE) :
                               (state_q == WB_CACHELINE_FLUSH) ? FLUSH_REQ_STATUS :
-                              (state_q == WB_CACHELINE_AMO) ? AMO_REQ :
+                              (state_q == WB_CACHELINE_AMO) ? WB_CACHELINE_AMO_WAIT_ACK :
                               IDLE;
                 end
             end
 
+            // ~> write back before AMO needs to wait until write is completely finished
+            WB_CACHELINE_AMO_WAIT_ACK: begin
+                if (valid_miss_fsm) begin
+                    state_d = AMO_REQ;
+                end
+            end
+
+
             // ------------------------------
             // Flushing & Initialization
             // ------------------------------