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frontend/axi/LiteDRAMAXI2NativeW: be sure that we already have the data before sending the command to the controller

This commit is contained in:
Florent Kermarrec 2018-12-01 12:11:22 +01:00
parent 0d5e5543fb
commit ebb1d3c762
1 changed files with 15 additions and 2 deletions
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17
litedram/frontend/axi.py
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@ -180,9 +180,22 @@ class LiteDRAMAXI2NativeW(Module):
] ]
# Command # 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)
)
]
self.comb += [ self.comb += [
# Emits the command only if we have the data # Emits the command if we have the data for it since
If(w_buffer.source.valid, # the controller can request it a any time.
If(w_buffer.level > cmd_in_flight,
self.cmd_request.eq(aw.valid), self.cmd_request.eq(aw.valid),
If(self.cmd_grant, If(self.cmd_grant,
port.cmd.valid.eq(aw.valid), port.cmd.valid.eq(aw.valid),