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frontend/avalon: Decouple Cmd and Data-paths in BURST-READ (We don't need to wait rdata.valid to return to Idle).

This commit is contained in:
Florent Kermarrec 2023-06-01 08:54:55 +02:00
parent c3963a1887
commit 5a092dd4ed
1 changed files with 8 additions and 17 deletions
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25
litedram/frontend/avalon.py
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@ -53,8 +53,6 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
burst_count = Signal(9)
address = Signal(port.address_width)
address_offset = Signal(port.address_width)
cmd_ready_seen = Signal()
cmd_ready_count = Signal(9)
self.comb += address_offset.eq(base_address >> log2_int(port.data_width//8))
# Write Data-path.
@ -85,7 +83,6 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
self.fsm = fsm = FSM(reset_state="IDLE")
fsm.act("IDLE",
avalon.waitrequest.eq(1),
NextValue(cmd_ready_seen, 0),
# Start of Access.
If(avalon.read | avalon.write,
NextValue(burst_count, avalon.burstcount),
@ -97,7 +94,6 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
),
If(avalon.read,
avalon.waitrequest.eq(0),
NextValue(cmd_ready_count, avalon.burstcount),
NextState("BURST-READ")
)
# Single Access.
@ -153,19 +149,14 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
avalon.waitrequest.eq(1),
port.cmd.addr.eq(address),
port.cmd.we.eq(0),
port.cmd.valid.eq(~cmd_ready_seen),
If(port.cmd.ready,
If(cmd_ready_count == 1,
NextValue(cmd_ready_seen, 1)
),
NextValue(cmd_ready_count, cmd_ready_count - 1),
NextValue(address, address + burst_increment)
),
If(port.rdata.valid,
If(burst_count == 1,
port.cmd.valid.eq(1),
port.cmd.last.eq(burst_count == 1),
If(port.cmd.valid & port.cmd.ready,
If(port.cmd.last,
NextState("IDLE")
),
NextValue(burst_count, burst_count - 1)
).Else(
NextValue(burst_count, burst_count - 1),
NextValue(address, address + burst_increment)
)
)
)