pipeline GW: remove cxp

pipeline GW: fix data loss when downstream not ack

src/gateware/cxp_pipeline.py

@@ -2,7 +2,6 @@ from migen import *
 from migen.genlib.cdc import MultiReg 
 from misoc.interconnect.csr import *
 from misoc.interconnect import stream
-from misoc.cores.liteeth_mini.mac.crc import LiteEthMACCRCEngine, LiteEthMACCRCChecker
 
 from functools import reduce
 from itertools import combinations
@@ -291,7 +290,6 @@ class RX_Debug_Buffer(Module,AutoCSR):
 class Duplicated_Char_Decoder(Module):
     def __init__(self):
         self.sink = stream.Endpoint(word_layout)
-        self.buffer = stream.Endpoint(word_layout)
         self.source = stream.Endpoint(word_layout_dchar)
 
         # # #
@@ -314,22 +312,23 @@ class Duplicated_Char_Decoder(Module):
         # Hence, a pipeline approach is needed to avoid any s/h violation, where the majority voting result are pre-calculate and injected into the bus immediate after the PHY.
         # And any downstream modules can access the voting result without implementing the voting logic inside the decoder
 
+        # cycle 1 - buffer data & calculate intermediate result  
+        buffer = stream.Endpoint(word_layout)
         self.sync += [
-            self.sink.ack.eq(self.buffer.ack),
-            self.buffer.stb.eq(self.sink.stb),
-            If(self.sink.stb,
-                self.buffer.data.eq(self.sink.data),
-                self.buffer.k.eq(self.sink.k),
-            ),
+            If((~buffer.stb | buffer.ack),
+                buffer.stb.eq(self.sink.stb),
+                buffer.payload.eq(self.sink.payload),
+            )
         ]
-
-        # cycle 1 - calculate ABC, ABD, ACD & BCD  
+        self.comb += self.sink.ack.eq(~buffer.stb | buffer.ack)
+        
+        # calculate ABC, ABD, ACD, BCD  
         char = [[self.sink.data[i*8:(i+1)*8], self.sink.k[i]] for i in range(4)]
         voters = [Record([("data", 8), ("k", 1)]) for _ in range(4)]
 
         for i, comb in enumerate(combinations(char, 3)):
             self.sync += [
-                If(self.sink.stb,
+                If((~buffer.stb | buffer.ack),
                     voters[i].data.eq(reduce(and_, [code[0] for code in comb])),
                     voters[i].k.eq(reduce(and_, [code[1] for code in comb])),
                 )
@@ -338,15 +337,16 @@ class Duplicated_Char_Decoder(Module):
 
         # cycle 2 - inject the voting result 
         self.sync += [
-            self.buffer.ack.eq(self.source.ack),
-            self.source.stb.eq(self.buffer.stb),
-            If(self.buffer.stb,
-                self.source.data.eq(self.buffer.data),
-                self.source.k.eq(self.buffer.k),
+            If((~self.source.stb | self.source.ack),
+                self.source.stb.eq(buffer.stb),
+                self.source.data.eq(buffer.data),
+                self.source.k.eq(buffer.k),
                 self.source.dchar.eq(Replicate(reduce(or_, [v.data for v in voters]), 4)),
                 self.source.dchar_k.eq(Replicate(reduce(or_, [v.k for v in voters]), 4)),
-            ),
+            )
         ]
+        self.comb += buffer.ack.eq(~self.source.stb | self.source.ack)
+
 
 @FullMemoryWE()
 class RX_Bootstrap(Module):
@@ -523,34 +523,3 @@ class Trigger_Ack_Checker(Module, AutoCSR):
                 )
             )
         )
-
-@ResetInserter()
-@CEInserter()
-class CXPCRC32(Module):
-    # Section 9.2.2.2 (CXP-001-2021)
-    width = 32
-    polynom = 0x04C11DB7
-    seed = 2**width-1
-    check = 0x00000000
-    def __init__(self, data_width):
-        self.data = Signal(data_width)
-        self.value = Signal(self.width)
-        self.error = Signal()
-
-        # # #
-
-        self.submodules.engine = LiteEthMACCRCEngine(data_width, self.width, self.polynom)
-        reg = Signal(self.width, reset=self.seed)
-        self.sync += reg.eq(self.engine.next)
-        self.comb += [
-            self.engine.data.eq(self.data),
-            self.engine.last.eq(reg),
-
-            self.value.eq(reg[::-1]),
-            self.error.eq(self.engine.next != self.check)
-        ]
-
-# For verifying crc in stream data packet
-class CXPCRC32Checker(LiteEthMACCRCChecker):
-    def __init__(self, layout):
-        LiteEthMACCRCChecker.__init__(self, CXPCRC32, layout)