[hw,dma,rtl] Only set error code when entering the error state

Previously, the error code is written when entering the error state AND while
being in there. Since the error code value is only availble in the transition
into the error state, and further update overwrites the error code again with
zero.

This change ensures that the error code only gets update in the transition into
the error state, where the correct value is available

Signed-off-by: Robert Schilling <[email protected]>

hw/ip/dma/rtl/dma.sv

@@ -76,7 +76,7 @@ module dma
 
   logic dma_state_error;
   dma_ctrl_state_e ctrl_state_q, ctrl_state_d;
-  logic clear_go, clear_status, clear_sha_status;
+  logic set_error_code, clear_go, clear_status, clear_sha_status;
 
   logic [INTR_CLEAR_SOURCES_WIDTH-1:0] clear_index_d, clear_index_q;
   logic                                clear_index_en, intr_clear_tlul_rsp_valid;
@@ -1297,15 +1297,18 @@ module dma
       end
     end
 
+    // Set the error code only when entering the error state
+    set_error_code = (ctrl_state_q != DmaError) && (ctrl_state_d == DmaError);
+
     // Fiddle out error signals
-    hw2reg.error_code.src_addr_error.de    = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.dst_addr_error.de    = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.opcode_error.de      = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.size_error.de        = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.bus_error.de         = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.base_limit_error.de  = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.range_valid_error.de = (ctrl_state_d == DmaError) | clear_status;
-    hw2reg.error_code.asid_error.de        = (ctrl_state_d == DmaError) | clear_status;
+    hw2reg.error_code.src_addr_error.de    = set_error_code | clear_status;
+    hw2reg.error_code.dst_addr_error.de    = set_error_code | clear_status;
+    hw2reg.error_code.opcode_error.de      = set_error_code | clear_status;
+    hw2reg.error_code.size_error.de        = set_error_code | clear_status;
+    hw2reg.error_code.bus_error.de         = set_error_code | clear_status;
+    hw2reg.error_code.base_limit_error.de  = set_error_code | clear_status;
+    hw2reg.error_code.range_valid_error.de = set_error_code | clear_status;
+    hw2reg.error_code.asid_error.de        = set_error_code | clear_status;
 
     hw2reg.error_code.src_addr_error.d     = clear_status? '0 : next_error[DmaSrcAddrErr];
     hw2reg.error_code.dst_addr_error.d     = clear_status? '0 : next_error[DmaDstAddrErr];