drtio-eem: remove unnecessary rtio_rx clock domain

artiq/gateware/drtio/core.py

@@ -27,9 +27,10 @@ class ChannelInterface:
 
 
 class TransceiverInterface(AutoCSR):
-    def __init__(self, channel_interfaces):
+    def __init__(self, channel_interfaces, *, async_rx=True):
         self.stable_clkin = CSRStorage()
         self.txenable = CSRStorage(len(channel_interfaces))
+        if async_rx:
             for i in range(len(channel_interfaces)):
                 name = "rtio_rx" + str(i)
                 setattr(self.clock_domains, "cd_"+name, ClockDomain(name=name))

artiq/gateware/drtio/rx_synchronizer.py

@@ -2,6 +2,12 @@ from migen import *
 from migen.genlib.cdc import ElasticBuffer
 
 
+class NoRXSynchronizer:
+    """To be used when RX is already synchronous (e.g. IOSERDES based PHY)."""
+    def resync(self, signal):
+        return signal
+
+
 class GenericRXSynchronizer(Module):
     """Simple RX synchronizer based on the portable Migen elastic buffer.
 

artiq/gateware/drtio/transceiver/eem_serdes.py

@@ -472,10 +472,4 @@ class EEMSerdes(Module, TransceiverInterface, AutoCSR):
 
         self.submodules += serdes_list
 
-        TransceiverInterface.__init__(self, channel_interfaces)
-
-        for i in range(len(serdes_list)):
-            self.comb += [
-                getattr(self, "cd_rtio_rx" + str(i)).clk.eq(ClockSignal()),
-                getattr(self, "cd_rtio_rx" + str(i)).rst.eq(ResetSignal())
-            ]
+        TransceiverInterface.__init__(self, channel_interfaces, async_rx=False)

artiq/gateware/targets/efc.py

@@ -14,7 +14,7 @@ from artiq.gateware import rtio
 from artiq.gateware.rtio.xilinx_clocking import fix_serdes_timing_path
 from artiq.gateware.rtio.phy import ttl_simple
 from artiq.gateware.drtio.transceiver import eem_serdes
-from artiq.gateware.drtio.rx_synchronizer import XilinxRXSynchronizer
+from artiq.gateware.drtio.rx_synchronizer import NoRXSynchronizer
 from artiq.gateware.drtio import *
 from artiq.build_soc import *
 
@@ -69,11 +69,10 @@ class Satellite(BaseSoC, AMPSoC):
 
         self.submodules.rtio_tsc = rtio.TSC(glbl_fine_ts_width=3)
 
-        cdr = ClockDomainsRenamer({"rtio_rx": "rtio_rx0"})
-        self.submodules.rx_synchronizer = cdr(XilinxRXSynchronizer())
+        cdr = ClockDomainsRenamer({"rtio_rx": "sys"})
         core = cdr(DRTIOSatellite(
             self.rtio_tsc, self.eem_transceiver.channels[0],
-            self.rx_synchronizer))
+            NoRXSynchronizer()))
         self.submodules.drtiosat = core
         self.csr_devices.append("drtiosat")