util_do_ram: Fix Rx path for interrupted transfers

When capture length is not programmed the DMA will interrupt the
transfer once it received all the samples he was set in its descriptor,
this case must be handled by resetting the read process and returning
an end of transfer (eot) to the data offload control logic.

Author: ronagyl

library/util_do_ram/util_do_ram.v

@@ -185,7 +185,9 @@ ad_mem_asym #(
 reg rd_active = 1'b0;
 reg [1:0] rd_req_cnt = 2'b0;
 always @(posedge m_axis_aclk) begin
-  if (rd_request_valid & rd_request_ready)
+  if (~rd_request_enable)
+    rd_req_cnt <= 2'b0;
+  else if (rd_request_valid & rd_request_ready)
     rd_req_cnt <= rd_req_cnt + 2'b1;
   else if (rd_response_eot)
     rd_req_cnt <= rd_req_cnt - 2'b1;
@@ -198,12 +200,17 @@ always @(posedge m_axis_aclk) begin
     rd_length <= rd_request_length[LENGTH_WIDTH-1:DST_ADDR_ALIGN];
 end
 
+wire rd_early_finish;
+
+assign rd_early_finish = rd_active & ~rd_request_enable;
 assign rd_last_beat = (rd_addr == rd_length) & rd_enable;
-assign rd_response_eot = m_axis_last & m_axis_valid & m_axis_ready;
+assign rd_response_eot = (m_axis_last & m_axis_valid & m_axis_ready) || rd_early_finish;
 
 // Read logic
 always @(posedge m_axis_aclk) begin
-  if (rd_request_valid & rd_request_ready)
+  if (~rd_request_enable)
+    rd_active <= 1'b0;
+  else if (rd_request_valid & rd_request_ready)
     rd_active <= 1'b1;
   else if (rd_last_beat)
     rd_active <= rd_req_cnt == 2;
@@ -256,7 +263,7 @@ util_axis_fifo #(
   .M_AXIS_REGISTERED(0)
 ) i_rd_fifo (
   .s_axis_aclk(m_axis_aclk),
-  .s_axis_aresetn(m_axis_aresetn),
+  .s_axis_aresetn(m_axis_aresetn & rd_request_enable),
   .s_axis_valid(rd_fifo_s_valid),
   .s_axis_ready(rd_fifo_s_ready),
   .s_axis_full(),
@@ -267,7 +274,7 @@ util_axis_fifo #(
   .s_axis_almost_full(),
 
   .m_axis_aclk(m_axis_aclk),
-  .m_axis_aresetn(m_axis_aresetn),
+  .m_axis_aresetn(m_axis_aresetn & rd_request_enable),
   .m_axis_valid(m_axis_valid),
   .m_axis_ready(m_axis_ready),
   .m_axis_data({m_axis_last,m_axis_data}),