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frontend/etherbone: Add 1-Slot PacketFIFO on LiteEthEtherboneProbe to prevent deadlock situation. 

Based on @Based on @david-sawatzke's analysis:
"Otherwise, depending on the caching in the path, a deadlock might occur due to the rx path being
blocked by the tx path, being blocked by the arp request, for which the answers get dropped in the
rx path."
This commit is contained in:
Florent Kermarrec 2021-11-08 11:42:44 +01:00
parent 8ba5cf06a6
commit 491c5ab150
1 changed files with 9 additions and 2 deletions
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11
liteeth/frontend/etherbone.py
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@ -139,14 +139,21 @@ class LiteEthEtherboneProbe(Module):
# # # # # #
self.submodules.fifo = fifo = PacketFIFO(eth_etherbone_packet_user_description(32),
payload_depth = 1,
param_depth = 1,
buffered = False
)
self.comb += sink.connect(fifo.sink)
self.submodules.fsm = fsm = FSM(reset_state="IDLE") self.submodules.fsm = fsm = FSM(reset_state="IDLE")
fsm.act("IDLE", fsm.act("IDLE",
If(sink.valid, If(fifo.source.valid,
NextState("PROBE_RESPONSE") NextState("PROBE_RESPONSE")
) )
) )
fsm.act("PROBE_RESPONSE", fsm.act("PROBE_RESPONSE",
sink.connect(source), fifo.source.connect(source),
source.pf.eq(0), source.pf.eq(0),
source.pr.eq(1), source.pr.eq(1),
If(source.valid & source.ready, If(source.valid & source.ready,