wr_endpoint/rx_path: don't store pfilter decision if frame is dropped by rx_buffer

If there is a storm of frames and rx_buffer gets full it starts to drop frames. However, before this commit even if a frame was dropped that way, U_match_buffer was storing pfilter decision for that frame. As a result decisions coming out from the match_buffer were shifted and applied to wrong frames. With this commit I check if the rx_buffer is full at the beginning of frame and eventually block mbuf_we so that the pfilter decision is not stored.

wr_endpoint/rx_path: don't store pfilter decision if frame is dropped by rx_buffer
If there is a storm of frames and rx_buffer gets full it starts to drop frames. However, before this commit even if a frame was dropped that way, U_match_buffer was storing pfilter decision for that frame. As a result decisions coming out from the match_buffer were shifted and applied to wrong frames. With this commit I check if the rx_buffer is full at the beginning of frame and eventually block mbuf_we so that the pfilter decision is not stored.
8c23ba5d · Grzegorz Daniluk · 87ad0d56 · 8c23ba5d · 8c23ba5d
Commit 8c23ba5d authored Feb 05, 2015 by Grzegorz Daniluk
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ep_rx_buffer.vhd modules/wr_endpoint/ep_rx_buffer.vhd +3 -0

ep_rx_path.vhd modules/wr_endpoint/ep_rx_path.vhd +28 -2

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--- a/modules/wr_endpoint/ep_rx_buffer.vhd
+++ b/modules/wr_endpoint/ep_rx_buffer.vhd
@@ -60,6 +60,7 @@ entity ep_rx_buffer is
    src_dreq_i : in  std_logic;

    level_o : out std_logic_vector(7 downto 0);
+    full_o  : out std_logic;
    regs_i  : in  t_ep_out_registers;
    rmon_o  : out t_rmon_triggers
    );
@@ -177,6 +178,8 @@ architecture behavioral of ep_rx_buffer is
  signal out_cur_addr : std_logic_vector(1 downto 0);
  
 begin
+
+  full_o <= q_drop;
 
  p_fifo_write : process(clk_sys_i)
  begin

--- a/modules/wr_endpoint/ep_rx_path.vhd
+++ b/modules/wr_endpoint/ep_rx_path.vhd
@@ -268,6 +268,7 @@ architecture behavioral of ep_rx_path is
      src_fab_o  : out t_ep_internal_fabric;
      src_dreq_i : in  std_logic;
      level_o    : out std_logic_vector(7 downto 0);
+      full_o     : out std_logic;
      regs_i     : in  t_ep_out_registers;
      rmon_o     : out t_rmon_triggers);
  end component;
@@ -327,6 +328,10 @@ architecture behavioral of ep_rx_path is
  signal rtu_rq_valid                                           : std_logic;
  signal stat_reg_mbuf_valid  : std_logic;

+  signal rxbuf_full       : std_logic;
+  signal rxbuf_drop_frame : std_logic;
+  signal rxbuf_got_sof    : std_logic;
+
 begin  -- behavioral

  fab_pipe(0) <= pcs_fab_i;
@@ -383,8 +388,9 @@ begin  -- behavioral
    pfilter_pclass <= (others => '0');
  end generate gen_without_packet_filter;

-  mbuf_we <= '1' when ((ematch_done='1' and g_with_early_match) or
-                       (pfilter_done='1' and g_with_dpi_classifier)) else
+  mbuf_we <= '1' when (((ematch_done='1' and g_with_early_match) or
+                       (pfilter_done='1' and g_with_dpi_classifier)) and
+                       rxbuf_drop_frame='0') else
             '0';

  gen_with_match_buff: if( g_with_early_match or g_with_dpi_classifier) generate
@@ -536,6 +542,7 @@ begin  -- behavioral
        src_fab_o  => fab_pipe(8),
        src_dreq_i => dreq_pipe(8),
        level_o    => fc_buffer_occupation_o,
+        full_o     => rxbuf_full,
        regs_i     => regs_i,
        rmon_o     => open);
  end generate gen_with_rx_buffer;
@@ -543,8 +550,27 @@ begin  -- behavioral
  gen_without_rx_buffer : if (not g_with_rx_buffer) generate
    fab_pipe(8)  <= fab_pipe(7);
    dreq_pipe(7) <= dreq_pipe(8);
+    rxbuf_full  <= '0';
  end generate gen_without_rx_buffer;

+  -- If rx_buffer was full at the beginning of the frame, that means this frame
+  -- won't be stored there at all. In this process I detect if rxbuf_full is
+  -- high when first data word of each frame is valid.
+  process(clk_sys_i)
+  begin
+    if rising_edge(clk_sys_i) then
+      if (rst_n_sys_i='0') then
+        rxbuf_drop_frame <= '0';
+        rxbuf_got_sof    <= '0';
+      elsif (fab_pipe(7).sof='1') then
+        rxbuf_got_sof <= '1';
+      elsif (rxbuf_got_sof='1' and fab_pipe(7).dvalid='1') then
+        rxbuf_drop_frame <= rxbuf_full;
+        rxbuf_got_sof    <= '0';
+      end if;
+    end if;
+  end process;
+
 --   U_RTU_Header_Extract : ep_rtu_header_extract
 --     generic map (
 --       g_with_rtu => g_with_rtu)