diff --git a/litedram/core/bankmachine.py b/litedram/core/bankmachine.py index aef06f9..c9068b6 100644 --- a/litedram/core/bankmachine.py +++ b/litedram/core/bankmachine.py @@ -35,35 +35,31 @@ class BankMachine(Module): ba = settings.geom.bankbits self.cmd = cmd = stream.Endpoint(cmd_request_rw_layout(a, ba)) - row_last = Signal(settings.geom.rowbits); + # # # + auto_precharge = Signal() - # # # slicer = _AddressSlicer(settings.geom.colbits, address_align) - # Row Change buffer - # Note: This would be a lot better if we could instead peek at the next value from cmd_buffer - rowchg_buffer_layout = [("differentRow", 1)] - rowchg_buffer = stream.SyncFIFO(rowchg_buffer_layout, settings.cmd_buffer_depth-1) - self.submodules += rowchg_buffer - # Command buffer cmd_buffer_layout = [("we", 1), ("adr", len(req.adr))] - cmd_buffer = stream.SyncFIFO(cmd_buffer_layout, settings.cmd_buffer_depth) - self.submodules += cmd_buffer + cmd_buffer0 = stream.SyncFIFO(cmd_buffer_layout, settings.cmd_buffer_depth-1) + cmd_buffer1 = stream.Buffer(cmd_buffer_layout) # 1 depth buffer to detect row change + self.submodules += cmd_buffer0, cmd_buffer1 self.comb += [ - req.connect(cmd_buffer.sink, omit=["wdata_valid", "wdata_ready", - "rdata_valid", "rdata_ready", - "lock"]), - cmd_buffer.source.ready.eq(req.wdata_ready | req.rdata_valid), - req.lock.eq(cmd_buffer.source.valid), + req.connect(cmd_buffer0.sink, omit=["wdata_valid", "wdata_ready", + "rdata_valid", "rdata_ready", + "lock"]), + cmd_buffer0.source.connect(cmd_buffer1.sink), + cmd_buffer1.source.ready.eq(req.wdata_ready | req.rdata_valid), + req.lock.eq(cmd_buffer1.source.valid), ] # Row tracking has_openrow = Signal() openrow = Signal(settings.geom.rowbits, reset_less=True) hit = Signal() - self.comb += hit.eq(openrow == slicer.row(cmd_buffer.source.adr)) + self.comb += hit.eq(openrow == slicer.row(cmd_buffer1.source.adr)) track_open = Signal() track_close = Signal() self.sync += \ @@ -71,19 +67,17 @@ class BankMachine(Module): has_openrow.eq(0) ).Elif(track_open, has_openrow.eq(1), - openrow.eq(slicer.row(cmd_buffer.source.adr)) + openrow.eq(slicer.row(cmd_buffer1.source.adr)) ) - #Set row change buffer + # Auto Precharge self.comb += [ - rowchg_buffer.sink.differentRow.eq(slicer.row(req.adr) != row_last), - rowchg_buffer.sink.valid.eq(cmd_buffer.source.valid & cmd_buffer.sink.valid & cmd_buffer.sink.ready), - rowchg_buffer.source.ready.eq(cmd_buffer.source.ready), - auto_precharge.eq(rowchg_buffer.source.differentRow & rowchg_buffer.source.valid & (track_close == 0)), - ] - self.sync += [ - If(cmd_buffer.sink.valid & cmd_buffer.sink.ready, - row_last.eq(slicer.row(req.adr)) + # If both buffers have data to output, check row to see + # if we can embed an autoprecharge in current cmd. + If(cmd_buffer0.source.valid & cmd_buffer1.source.valid, + If(slicer.row(cmd_buffer0.source.adr) != slicer.row(cmd_buffer1.source.adr), + auto_precharge.eq((track_close == 0)) + ) ) ] @@ -92,9 +86,9 @@ class BankMachine(Module): self.comb += [ cmd.ba.eq(n), If(sel_row_adr, - cmd.a.eq(slicer.row(cmd_buffer.source.adr)) + cmd.a.eq(slicer.row(cmd_buffer1.source.adr)) ).Else( - cmd.a.eq((auto_precharge << 10) | slicer.col(cmd_buffer.source.adr)) + cmd.a.eq((auto_precharge << 10) | slicer.col(cmd_buffer1.source.adr)) ) ] @@ -110,13 +104,13 @@ class BankMachine(Module): fsm.act("REGULAR", If(self.refresh_req, NextState("REFRESH") - ).Elif(cmd_buffer.source.valid, + ).Elif(cmd_buffer1.source.valid, If(has_openrow, If(hit, # Note: write-to-read specification is enforced by # multiplexer cmd.valid.eq(1), - If(cmd_buffer.source.we, + If(cmd_buffer1.source.we, req.wdata_ready.eq(cmd.ready), cmd.is_write.eq(1), cmd.we.eq(1),