From 0e25154e25ead77b402225bcd44531938833d02a Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sat, 16 Sep 2017 15:19:30 +0800
Subject: [PATCH] rtio/sed: quash writes to LogChannel

---
 artiq/gateware/rtio/core.py                 |  4 +++-
 artiq/gateware/rtio/sed/core.py             |  4 +++-
 artiq/gateware/rtio/sed/lane_distributor.py | 19 +++++++++++++------
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/artiq/gateware/rtio/core.py b/artiq/gateware/rtio/core.py
index 87c5975ee..8492e31f4 100644
--- a/artiq/gateware/rtio/core.py
+++ b/artiq/gateware/rtio/core.py
@@ -222,7 +222,9 @@ class Core(Module, AutoCSR):
         self.submodules += inputs
 
         # Outputs
-        outputs = SED(channels, "async", interface=self.cri)
+        outputs = SED(channels, "async",
+            quash_channels=[n for n, c in enumerate(channels) if isinstance(c, LogChannel)],
+            interface=self.cri)
         self.submodules += outputs
         self.comb += outputs.coarse_timestamp.eq(coarse_ts)
         self.sync += outputs.minimum_coarse_timestamp.eq(coarse_ts + 16)
diff --git a/artiq/gateware/rtio/sed/core.py b/artiq/gateware/rtio/sed/core.py
index ba87191ad..30f16a863 100644
--- a/artiq/gateware/rtio/sed/core.py
+++ b/artiq/gateware/rtio/sed/core.py
@@ -12,7 +12,8 @@ __all__ = ["SED"]
 
 
 class SED(Module):
-    def __init__(self, channels, mode, enable_spread=True, lane_count=8, fifo_depth=128, interface=None):
+    def __init__(self, channels, mode, lane_count=8, fifo_depth=128, enable_spread=True,
+                 quash_channels=[], interface=None):
         if mode == "sync":
             lane_dist_cdr = lambda x: x
             fifos_cdr = lambda x: x
@@ -34,6 +35,7 @@ class SED(Module):
             LaneDistributor(lane_count, seqn_width,
                             layouts.fifo_payload(channels), fine_ts_width,
                             enable_spread=enable_spread,
+                            quash_channels=quash_channels,
                             interface=interface))
         self.submodules.fifos = fifos_cdr(
             FIFOs(lane_count, fifo_depth,
diff --git a/artiq/gateware/rtio/sed/lane_distributor.py b/artiq/gateware/rtio/sed/lane_distributor.py
index aee932157..986d7a470 100644
--- a/artiq/gateware/rtio/sed/lane_distributor.py
+++ b/artiq/gateware/rtio/sed/lane_distributor.py
@@ -8,13 +8,13 @@ __all__ = ["LaneDistributor"]
 
 
 # CRI write happens in 3 cycles:
-# 1. set timestamp
+# 1. set timestamp and channel
 # 2. set other payload elements and issue write command
 # 3. check status
 
 class LaneDistributor(Module):
     def __init__(self, lane_count, seqn_width, layout_payload, fine_ts_width,
-                 enable_spread=True, interface=None):
+                 enable_spread=True, quash_channels=[], interface=None):
         if lane_count & (lane_count - 1):
             raise NotImplementedError("lane count must be a power of 2")
 
@@ -52,7 +52,7 @@ class LaneDistributor(Module):
             if hasattr(lio.payload, "data"):
                 self.comb += lio.payload.data.eq(self.cri.o_data)
 
-        # when timestamp arrives in cycle #1, prepare computations
+        # when timestamp and channel arrive in cycle #1, prepare computations
         coarse_timestamp = Signal(64-fine_ts_width)
         self.comb += coarse_timestamp.eq(self.cri.timestamp[fine_ts_width:])
         timestamp_above_min = Signal()
@@ -76,6 +76,11 @@ class LaneDistributor(Module):
             )
         ]
 
+        quash = Signal()
+        self.sync += quash.eq(0)
+        for channel in quash_channels:
+            self.sync += If(self.cri.chan_sel[:16] == channel, quash.eq(1))
+
         # cycle #2, write
         timestamp_above_lane_min = Signal()
         do_write = Signal()
@@ -83,9 +88,11 @@ class LaneDistributor(Module):
         do_sequence_error = Signal()
         self.comb += [
             timestamp_above_lane_min.eq(Mux(use_laneB, timestamp_above_laneB_min, timestamp_above_laneA_min)),
-            do_write.eq((self.cri.cmd == cri.commands["write"]) & timestamp_above_min & timestamp_above_lane_min),
-            do_underflow.eq((self.cri.cmd == cri.commands["write"]) & ~timestamp_above_min),
-            do_sequence_error.eq((self.cri.cmd == cri.commands["write"]) & timestamp_above_min & ~timestamp_above_lane_min),
+            If(~quash,
+                do_write.eq((self.cri.cmd == cri.commands["write"]) & timestamp_above_min & timestamp_above_lane_min),
+                do_underflow.eq((self.cri.cmd == cri.commands["write"]) & ~timestamp_above_min),
+                do_sequence_error.eq((self.cri.cmd == cri.commands["write"]) & timestamp_above_min & ~timestamp_above_lane_min),
+            ),
             Array(lio.we for lio in self.output)[use_lanen].eq(do_write)
         ]
         self.sync += [