frontend/stream: Add packet support and remove send_level.

TX packets are now sent when we have a full packet of when the FIFO is full.
Last can always be asserted from user-side when packet needs to be immediately
transmitted, the behavior will then be similar to previous implementation.

Errors are now also reported on RX.

liteeth/common.py

@@ -317,6 +317,10 @@ def eth_etherbone_mmap_description(dw):
     return EndpointDescription(payload_layout, param_layout)
 
 # TTY
-def eth_tty_description(dw):
+def eth_tty_tx_description(dw):
     payload_layout = [("data", dw)]
     return EndpointDescription(payload_layout)
+
+def eth_tty_rx_description(dw):
+    payload_layout = [("data", dw), ("error", 1)]
+    return EndpointDescription(payload_layout)

liteeth/frontend/stream.py

@@ -9,16 +9,15 @@
 # Stream to UDP TX -----------------------------------------------------------------------------------
 
 class LiteEthStream2UDPTX(Module):
-    def __init__(self, ip_address, udp_port, data_width=8, fifo_depth=None, send_level=1):
-        self.sink   = sink   = stream.Endpoint(eth_tty_description(data_width))
+    def __init__(self, ip_address, udp_port, data_width=8, fifo_depth=None):
+        self.sink   = sink   = stream.Endpoint(eth_tty_tx_description(data_width))
         self.source = source = stream.Endpoint(eth_udp_user_description(data_width))
 
         # # #
 
         ip_address = convert_ip(ip_address)
 
         if fifo_depth is None:
-            assert send_level == 1
             self.comb += [
                 sink.connect(source, keep={"valid", "ready", "data"}),
                 source.last.eq(1),
@@ -36,7 +35,8 @@ def __init__(self, ip_address, udp_port, data_width=8, fifo_depth=None, send_lev
 
             self.submodules.fsm = fsm = FSM(reset_state="IDLE")
             fsm.act("IDLE",
-                If(fifo.level >= send_level,
+                # Send FIFO contents when we have a full-packet or when FIFO is full.
+                If((fifo.source.valid & fifo.source.last) | ~fifo.sink.ready,
                     NextValue(level, fifo.level),
                     NextValue(counter, 0),
                     NextState("SEND")
@@ -65,7 +65,7 @@ def __init__(self, ip_address, udp_port, data_width=8, fifo_depth=None, send_lev
 class LiteEthUDP2StreamRX(Module):
     def __init__(self, ip_address=None, udp_port=None, data_width=8, fifo_depth=None, with_broadcast=True):
         self.sink   = sink   = stream.Endpoint(eth_udp_user_description(data_width))
-        self.source = source = stream.Endpoint(eth_tty_description(data_width))
+        self.source = source = stream.Endpoint(eth_tty_rx_description(data_width))
 
         # # #
 
@@ -83,14 +83,18 @@ def __init__(self, ip_address=None, udp_port=None, data_width=8, fifo_depth=None
         # Data-Path / Buffering (Optional).
         if fifo_depth is None:
             self.comb += [
-                sink.connect(source, keep={"last", "data"}),
+                sink.connect(source, keep={"last", "data", "error"}),
                 source.valid.eq(sink.valid & valid),
                 sink.ready.eq(source.ready | ~valid)
             ]
         else:
-            self.submodules.fifo = fifo = stream.SyncFIFO([("data", data_width)], fifo_depth, buffered=True)
+            self.submodules.fifo = fifo = stream.SyncFIFO(
+                layout   = [("data", data_width), ("error", 1)],
+                depth    = fifo_depth,
+                buffered = True,
+            )
             self.comb += [
-                sink.connect(fifo.sink, keep={"last", "data"}),
+                sink.connect(fifo.sink, keep={"last", "data", "error"}),
                 fifo.sink.valid.eq(sink.valid & valid),
                 sink.ready.eq(fifo.sink.ready | ~valid),
                 fifo.source.connect(source)

liteeth/gen.py

@@ -149,6 +149,7 @@ def get_udp_port_ios(name, data_width, dynamic_params=False):
             Subsignal("source_last",  Pins(1)),
             Subsignal("source_ready", Pins(1)),
             Subsignal("source_data",  Pins(data_width)),
+            Subsignal("source_error", Pins(1)),
         ),
     ]
 
@@ -342,7 +343,8 @@ def __init__(self, platform, core_config):
                 port_ios.source_valid.eq(udp_streamer.source.valid),
                 port_ios.source_last.eq(udp_streamer.source.last),
                 udp_streamer.source.ready.eq(port_ios.source_ready),
-                port_ios.source_data.eq(udp_streamer.source.data)
+                port_ios.source_data.eq(udp_streamer.source.data),
+                port_ios.source_error.eq(udp_streamer.source.error),
             ]
 
 # Build --------------------------------------------------------------------------------------------