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frontend/axi: simplify LiteDRAMAXI2NativeW logic

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Accept the Address/Data only if:
- Address & Data request are *both* valid.
- Data buffer is not full.
This commit is contained in:
Florent Kermarrec 2018-12-05 11:44:23 +01:00
parent 6778c72665
commit 282b60e94c
1 changed files with 15 additions and 26 deletions
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41
litedram/frontend/axi.py
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@ -180,39 +180,28 @@ class LiteDRAMAXI2NativeW(Module):
]
# Command
cmd_in_flight = Signal(max=buffer_depth)
cmd_in_flight_inc = Signal()
cmd_in_flight_dec = Signal()
self.sync += [
cmd_in_flight_inc.eq(aw.valid & aw.ready),
cmd_in_flight_dec.eq(port.wdata.valid & port.wdata.ready),
If(cmd_in_flight_inc & ~cmd_in_flight_dec,
cmd_in_flight.eq(cmd_in_flight + 1)
).Elif(~cmd_in_flight_inc & cmd_in_flight_dec,
cmd_in_flight.eq(cmd_in_flight - 1)
)
]
# Accept and send command to the controller only if:
# - Address & Data request are *both* valid.
# - Data buffer is not full.
self.comb += [
# Emits the command if we have the data for it since
# the controller can request it a any time.
If(w_buffer.level > cmd_in_flight,
self.cmd_request.eq(aw.valid),
If(self.cmd_grant,
port.cmd.valid.eq(aw.valid),
aw.ready.eq(port.cmd.ready),
port.cmd.we.eq(1),
port.cmd.addr.eq(aw.addr >> ashift)
self.cmd_request.eq(aw.valid & axi.w.valid & w_buffer.sink.ready),
If(self.cmd_request & self.cmd_grant,
port.cmd.valid.eq(1),
port.cmd.we.eq(1),
port.cmd.addr.eq(aw.addr >> ashift),
aw.ready.eq(port.cmd.ready),
axi.w.connect(w_buffer.sink, omit={"valid", "ready"}),
If(port.cmd.ready,
w_buffer.sink.valid.eq(1),
axi.w.ready.eq(1)
)
)
]
# Write Data
self.comb += [
axi.w.connect(w_buffer.sink),
If(id_buffer.source.valid,
w_buffer.source.connect(port.wdata, omit={"strb"}),
port.wdata.we.eq(w_buffer.source.strb)
)
w_buffer.source.connect(port.wdata, omit={"strb"}),
port.wdata.we.eq(w_buffer.source.strb)
]