u1p: implement a signal to indicate a partially full usb lut, to flush it

1 files changed, 16 insertions, 7 deletions

diff --git a/usrp2/gpif/gpif_rd.v b/usrp2/gpif/gpif_rd.v
index ed0721a36..728b8be78 100644
--- a/usrp2/gpif/gpif_rd.v
+++ b/usrp2/gpif/gpif_rd.v
@@ -3,6 +3,7 @@ module gpif_rd
   (input gpif_clk, input gpif_rst,
    output [15:0] gpif_data, input gpif_rd, input gpif_ep,
    output reg gpif_empty_d, output reg gpif_empty_c,
+   output reg gpif_flush,
    
    input sys_clk, input sys_rst,
    input [18:0] data_i, input src_rdy_i, output dst_rdy_o,
@@ -10,8 +11,9 @@ module gpif_rd
    output [31:0] debug
    );
    
-   wire [17:0] 	data_o, resp_o; // drop occ bit from input data
-   wire 	final_rdy_data, final_rdy_resp;
+   wire [18:0] 	 data_o; // occ bit indicates flush
+   wire [17:0] 	 resp_o; // no occ bit
+   wire 	 final_rdy_data, final_rdy_resp;
    
    // 33/257 Bug Fix
    reg [8:0] 	read_count;
@@ -24,10 +26,10 @@ module gpif_rd
        read_count <= 0;
 
    // Data Path
-   wire [17:0] 	data_int;
+   wire [18:0] 	data_int;
    wire 	src_rdy_int, dst_rdy_int;
-   fifo_2clock_cascade #(.WIDTH(18), .SIZE(4)) rd_fifo_2clk
-     (.wclk(sys_clk), .datain(data_i[17:0]), .src_rdy_i(src_rdy_i), .dst_rdy_o(dst_rdy_o), .space(),
+   fifo_2clock_cascade #(.WIDTH(19), .SIZE(4)) rd_fifo_2clk
+     (.wclk(sys_clk), .datain(data_i[18:0]), .src_rdy_i(src_rdy_i), .dst_rdy_o(dst_rdy_o), .space(),
       .rclk(~gpif_clk), .dataout(data_int), .src_rdy_o(src_rdy_int), .dst_rdy_i(dst_rdy_int), .occupied(),
       .arst(sys_rst));
 
@@ -37,7 +39,7 @@ module gpif_rd
    wire 	consume_sop = consume_data_line & final_rdy_data & data_o[16];
    wire 	consume_eop = consume_data_line & final_rdy_data & data_o[17];
    
-   fifo_cascade #(.WIDTH(18), .SIZE(10)) rd_fifo
+   fifo_cascade #(.WIDTH(19), .SIZE(10)) rd_fifo
      (.clk(~gpif_clk), .reset(gpif_rst), .clear(0),
       .datain(data_int), .src_rdy_i(src_rdy_int), .dst_rdy_o(dst_rdy_int), .space(),
       .dataout(data_o), .src_rdy_o(final_rdy_data), .dst_rdy_i(consume_data_line), .occupied());
@@ -56,7 +58,14 @@ module gpif_rd
        gpif_empty_d <= 1;
      else
        gpif_empty_d <= ~|packet_count;
-   	      
+
+   // Use occ bit to signal a gpif flush
+   always @(negedge gpif_clk)
+     if(gpif_rst)
+       gpif_flush <= 0;
+     else if(consume_eop & data_o[18])
+       gpif_flush <= ~gpif_flush;
+   
    // Response Path
    wire [15:0] 	resp_fifolevel;
    wire 	consume_resp_line = gpif_rd & gpif_ep & ~read_count[4];