From ccd4ea65032c450bff04503677bf6dfb91a2ea99 Mon Sep 17 00:00:00 2001
From: Eric Kooistra <kooistra@astron.nl>
Date: Thu, 14 Apr 2022 15:16:16 +0200
Subject: [PATCH] Use dp_sop instead of mm_done and explained why. This makes
the code for passing on dp_header_info more robust and clear.
---
.../sdp/src/vhdl/sdp_statistics_offload.vhd | 73 ++++++++++++++-----
1 file changed, 55 insertions(+), 18 deletions(-)
diff --git a/applications/lofar2/libraries/sdp/src/vhdl/sdp_statistics_offload.vhd b/applications/lofar2/libraries/sdp/src/vhdl/sdp_statistics_offload.vhd
index 1e66291922..9ec1557d8c 100644
--- a/applications/lofar2/libraries/sdp/src/vhdl/sdp_statistics_offload.vhd
+++ b/applications/lofar2/libraries/sdp/src/vhdl/sdp_statistics_offload.vhd
@@ -25,10 +25,12 @@
-- Purpose:
-- . SDP statistics offload
-- Description:
--- https://support.astron.nl/confluence/display/L2M/L5+SDPFW+Design+Document%3A+Subband+filterbank
--- . See figure 4.3
--- https://plm.astron.nl/polarion/#/project/LOFAR2System/wiki/L2%20Interface%20Control%20Documents/SC%20to%20SDP%20ICD
--- . See 2.9.4 Station Control (L3-SC) - SDP Firmware (L4-SDPFW)
+-- [1] https://support.astron.nl/confluence/display/L2M/L5+SDPFW+Design+Document%3A+Subband+filterbank
+-- . See figure 4.3
+-- [2] https://support.astron.nl/confluence/display/L2M/L5+SDPFW+Design+Document%3A+Subband+Correlator
+-- . See Figure 3.7
+-- [3] https://plm.astron.nl/polarion/#/project/LOFAR2System/wiki/L2%20Interface%20Control%20Documents/SC%20to%20SDP%20ICD
+-- . See 2.9.4 Station Control (L3-SC) - SDP Firmware (L4-SDPFW)
--
-- . endianess
-- Within a 32bit MM word the values are stored with LSByte at lowest byte
@@ -225,6 +227,7 @@ ARCHITECTURE str OF sdp_statistics_offload IS
SIGNAL trigger_en : STD_LOGIC := '0';
SIGNAL trigger_offload : STD_LOGIC := '0';
SIGNAL mm_done : STD_LOGIC := '0';
+ SIGNAL dp_sop : STD_LOGIC := '0';
SIGNAL dp_block_from_mm_src_out : t_dp_sosi;
SIGNAL dp_block_from_mm_src_in : t_dp_siso;
@@ -349,7 +352,7 @@ BEGIN
data_id_slv <= func_sdp_map_stat_data_id(g_statistics_type, data_id_rec);
- p_control_packet_offload : PROCESS(r, in_sosi, local_si_offset, trigger_offload, nof_crosslets, crosslets_info, nof_packets, mm_done, dp_header_info)
+ p_control_packet_offload : PROCESS(r, in_sosi, local_si_offset, trigger_offload, nof_crosslets, crosslets_info, nof_packets, dp_sop, dp_header_info)
VARIABLE v : t_reg;
VARIABLE v_index : NATURAL;
BEGIN
@@ -372,18 +375,33 @@ BEGIN
END IF;
END IF;
- -- Capture nof_crosslets and crosslets_info at in_sosi.sync, to make sure
- -- they do not change during packets offload. The trigger_offload occurs
- -- after the nof_cycles_dly and the offload will have finished before the
- -- next in_sosi.sync
+
+ -- For XST offload capture nof_crosslets and crosslets_info at in_sosi.sync,
+ -- to make sure they do not change during packets offload.
+ -- . The sdp_crosslets_subband_select.vhd takes in [2] takes care that
+ -- nof_crosslets and crosslets_info are valid at the xsel_sosi.sync. The
+ -- mmp_dp_bsn_align_v2 in [2] then aligns the local xsel_sosi with the
+ -- remote data and passes on the sync. After some latency the sync
+ -- arrives at the sdp_statistics_offload. This latency is very short
+ -- compared to the sync period, so the nof_crosslets and crosslet_info
+ -- are still valid at the in_sosi.sync.
IF in_sosi.sync = '1' THEN
v.nof_crosslets := TO_UINT(nof_crosslets);
v.crosslets_info_rec := func_sdp_map_crosslets_info(crosslets_info);
END IF;
- -- Issue start_pulse per packet offload
+ -- The trigger_offload occurs nof_cycles_dly after the in_sosi.sync and the
+ -- offload will have finished before the next in_sosi.sync, because
+ -- c_sdp_offload_time is such that all offload will finish within 100 ms
+ -- and the integration interval (= sync interval) is 1 s for SST and BST
+ -- and minimal 0.1s (= c_sdp_xst_nof_clk_per_sync_min) for XST.
+ -- The trigger_offload initializes the control for the first packet offload
+ -- in every sync interval.
+ -- . Issue a start_pulse per packet offload. The start_pulse is used by
+ -- u_dp_block_from_mm_dc to read the packet from statistics memory.
IF trigger_offload = '1' THEN
- -- Use trigger_offload to start first packet offload, all g_statistics_type start from start address 0
+ -- Use trigger_offload to start first packet offload, all
+ -- g_statistics_type start from start address 0
v.start_pulse := '1';
v.sync := '1';
v.start_address := 0;
@@ -394,8 +412,20 @@ BEGIN
v.instance_count := 0; -- only used for XST
v.instance_address := 0; -- only used for XST
- ELSIF mm_done = '1' THEN
- -- Use mm_done to start next packets offloads.
+ -- The dp_sop = '1' when the packet has been read from statistics memory
+ -- and is about to get out of the dp_fifo_fill_eop in
+ -- u_dp_block_from_mm_dc. The difference between dp_sop and the mm_done
+ -- output of u_dp_block_from_mm_dc, is that dp_sop also includes any
+ -- dp_fifo_fill_eop latency. This ensures that the dp_sop identifies the
+ -- sop of the offload packet. At the dp_sop:
+ -- . the dp_header_info per packet offload can be released
+ -- . the next packet offload can be prepared
+ --
+ ELSIF dp_sop = '1' THEN
+ -- Release dp_header_info for current packet offload
+ v.dp_header_info := dp_header_info;
+
+ -- Start next packets offload.
IF r.packet_count < nof_packets - 1 THEN
IF g_statistics_type = "SST" THEN
-- step step step step step step
@@ -444,10 +474,6 @@ BEGIN
END IF;
END IF;
- -- Release dp_header_info per packet offload
- IF trigger_offload = '1' OR mm_done = '1' THEN
- v.dp_header_info := dp_header_info;
- END IF;
nxt_r <= v;
END PROCESS;
@@ -487,13 +513,24 @@ BEGIN
sync_in => r.sync,
bsn_at_sync => bsn_at_sync,
start_address => r.start_address,
- done => mm_done,
+ done => mm_done, -- not used, use dp_sop instead
mm_mosi => master_mosi,
mm_miso => master_miso,
out_sosi => dp_block_from_mm_src_out,
out_siso => dp_block_from_mm_src_in
);
+ -- Use dp_block_from_mm_src_out.sop as dp_sop, to include the
+ -- dp_fifo_fill_eop that is in dp_block_from_mm_dc. The dp_sop thus is the
+ -- sop of the packet that is about to be offloaded by u_dp_offload_tx_v3.
+ -- The r.dp_header_info must be available at the dp_offload_snk_in.sop.
+ -- This is guaranteed because:
+ -- . r.dp_header_info is available one clock cycle after dp_sop in
+ -- p_control_packet_offload.
+ -- . The dp_offload_snk_in is delayed also by one clock cycle by
+ -- u_dp_pipeline_ready.
+ dp_sop <= dp_block_from_mm_src_out.sop;
+
u_dp_pipeline_ready : ENTITY dp_lib.dp_pipeline_ready
PORT MAP(
rst => dp_rst,
--
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