cxp downconn: fix aligner not work @ 5 & 6.25Gbps

src/gateware/cxp_downconn.py

@@ -160,7 +160,7 @@ class CXP_DownConn(Module, AutoCSR):
             Instance("OBUF", i_I=gtx.cd_cxp_gtx_tx.clk, o_O=debug_sma.n_rx),
 
             # pmod 0-7 pin
-            Instance("OBUF", i_I=gtx.comma_det.rxinit_done, o_O=pmod_pads[0]),
+            Instance("OBUF", i_I=gtx.comma_det.word_aligned, o_O=pmod_pads[0]),
             Instance("OBUF", i_I=gtx.comma_det.restart, o_O=pmod_pads[1]),
             Instance("OBUF", i_I=gtx.comma_det.aligner_en_rxclk, o_O=pmod_pads[2]),
             Instance("OBUF", i_I=gtx.comma_det.check_reset, o_O=pmod_pads[3]),
@@ -331,7 +331,7 @@ class QPLL(Module):
 class Comma_Detector(Module):
     def __init__(self, comma, check_period=1_000_000):
         self.data = Signal(20)
-        self.rxinit_done = Signal()
+        self.word_aligned = Signal()
 
         self.aligner_en_rxclk = Signal()
         self.ready = Signal()
@@ -345,39 +345,6 @@ class Comma_Detector(Module):
         # - UG476 (v1.12.1) p.228
 
         # The validity of data & comma are checked externally
-        # aligned = Signal()
-        # valid_data = Signal()
-        # aligned_rxclk = Signal()
-        # valid_data_rxclk = Signal()
-        # rx1cnt = Signal(max=11)
-        # self.specials += [
-        #     MultiReg(aligned_rxclk, aligned),
-        #     MultiReg(valid_data_rxclk, valid_data),
-        # ]
-        # self.submodules.check_reset = check_reset = PulseSynchronizer("sys", "cxp_gtx_rx") 
-
-        # comma_n = ~comma & 0b1111111111
-        # self.sync.cxp_gtx_rx += [
-        #     If(check_reset.o,
-        #         aligned_rxclk.eq(0),
-        #     ).Elif((self.data[:10] == comma) | (self.data[:10] == comma_n),
-        #         aligned_rxclk.eq(1),
-        #     ),
-
-        #     rx1cnt.eq(reduce(add, [self.data[i] for i in range(10)])),
-        #     If(check_reset.o,
-        #         valid_data_rxclk.eq(0),
-        #     ).Elif((rx1cnt == 4) | (rx1cnt == 5) | (rx1cnt == 6),
-        #         valid_data_rxclk.eq(1),
-        #     ),
-        # ]
-
-        # self.aligned = Signal()
-        # self.valid_data = Signal()
-        # self.comb +=[
-        #     self.aligned.eq(aligned),
-        #     self.valid_data.eq(valid_data)
-        # ]
 
 
         check_counter = Signal(reset=check_period-1, max=check_period)
@@ -465,18 +432,31 @@ class Comma_Detector(Module):
 
         self.submodules.rxfsm = rxfsm = ClockDomainsRenamer("cxp_gtx_rx")(FSM(reset_state="ALIGNING"))
 
+        # the data from gtxe2 is delayed and checking at the output may not reflect the alignment inside the aligner
+        # thus, failing to alignment on high linerate >5Gbps is common due to the aligner_en being asserted longer than necessary and lead to a lose of lock
+        # a timer is used to wait till the "aligned" data to arrive and do a system check like the datasheet suggested
+        self.submodules.timer = timer = ClockDomainsRenamer("cxp_gtx_rx")(WaitTimer(5000))
+
         rxfsm.act("ALIGNING",
             self.aligner_en_rxclk.eq(1),
-            If(comma_aligned & (~has_error),
+            If(self.word_aligned,
                 check_reset.eq(1),
-                NextState("DOUBLE_CHECK"),               
+                NextState("WAIT_ALIGNED_DATA"),               
             )
         )
 
-        rxfsm.act("DOUBLE_CHECK",
+        rxfsm.act("WAIT_ALIGNED_DATA",
+            timer.wait.eq(1),
+            If(timer.done,
+                check_reset.eq(1),
+                NextState("CHECKING"),
+            )
+        )
+
+        rxfsm.act("CHECKING",
             If(check,
                 check_reset.eq(1),
-                If(~error_seen,
+                If(comma_seen & (~error_seen),
                    NextState("READY"),
                 ).Else(
                     NextState("ALIGNING")
@@ -490,62 +470,12 @@ class Comma_Detector(Module):
             ready.eq(1),
             If(check,
                 check_reset.eq(1),
-                If(~comma_seen,
+                If(~(comma_seen & (~error_seen)),
                     NextState("ALIGNING"),
                 )
             )
         )
 
-        
-        # self.submodules.fsm = fsm = FSM(reset_state="WAIT_RXINIT")
-
-        # aligner_en = Signal()
-        # self.specials += MultiReg(aligner_en, self.aligner_en_rxclk, odomain="cxp_gtx_rx")
-
-        # fsm.act("WAIT_RXINIT",
-        #     If(self.rxinit_done,
-        #         NextState("WAIT_COMMA_ALIGN"),   
-        #     )
-        # )
-        
-        # fsm.act("WAIT_COMMA_ALIGN",
-        #     aligner_en.eq(1),
-        #     If(check,
-        #         check_reset.i.eq(1),
-        #         If(aligned,
-        #             NextState("WAIT_VALID_DATA"),
-        #         ).Else(
-        #             self.restart.eq(1),   
-        #             NextState("WAIT_RXINIT")
-        #         )
-        #     )
-        # )
-
-        # fsm.act("WAIT_VALID_DATA",
-        #     aligner_en.eq(1),
-        #     If(check,
-        #         check_reset.i.eq(1),
-        #         If(aligned & valid_data,
-        #             NextState("READY"),
-        #         ).Else(
-        #             self.restart.eq(1),   
-        #             NextState("WAIT_RXINIT"),
-        #         )
-        #     )
-        # )
-
-        # fsm.act("READY",
-        #     self.ready.eq(1),
-        #     If(check,
-        #         check_reset.i.eq(1),
-        #         If(~(aligned & valid_data),
-        #             self.restart.eq(1),   
-        #             NextState("WAIT_RXINIT"),
-        #         )
-        #     )
-        # )
-
-        
 
 class GTX(Module):
     # Settings:
@@ -609,6 +539,7 @@ class GTX(Module):
         txdata = Signal(40)
         rxdata = Signal(40)
 
+        word_aligned = Signal()
         comma_aligner_en = Signal()
         # Note: the following parameters were set after consulting AR45360
         self.specials += \
@@ -752,6 +683,7 @@ class GTX(Module):
                 i_RXMCOMMAALIGNEN=comma_aligner_en,
                 i_RXCOMMADETEN=1,
                 i_RXSLIDE=0,
+                o_RXBYTEISALIGNED=word_aligned,
 
                 # RX 8B/10B Decoder Attributes
                 p_RX_DISPERR_SEQ_MATCH="FALSE",
@@ -893,7 +825,7 @@ class GTX(Module):
         self.submodules.comma_det = comma_det = Comma_Detector(0b0101111100)
         self.comb += [
             comma_det.data.eq(rxdata),
-            comma_det.rxinit_done.eq(rx_init.done),
+            comma_det.word_aligned.eq(word_aligned),
             comma_aligner_en.eq(comma_det.aligner_en_rxclk),
             self.rx_ready.eq(comma_det.ready),