Jep, there definitly is a regression with the xrx200 switch.
OpenWrt 19.07.7 Kernel 4.14.221 supports ports 3 + 4
Openwrt 21.02.0-rc1 Kernel 5.4.111 ports 3 + 4 are dead
root@OpenWrt:~# dmesg|grep -A5 -B5 PHY
[ 0.163028] pinctrl core: initialized pinctrl subsystem
[ 0.170653] NET: Registered protocol family 16
[ 0.183980] dcdc-xrx200 1f106a00.dcdc: Core Voltage : 1016 mV
[ 0.198588] pinctrl-xway 1e100b10.pinmux: Init done
[ 0.205140] dma-xway 1e104100.dma: Init done - hw rev: 7, ports: 7, channels: 28
[ 0.216895] pcie-xrx200 1d900000.pcie: failed to get the PCIe PHY
[ 0.265910] usbcore: registered new interface driver usbfs
[ 0.271499] usbcore: registered new interface driver hub
[ 0.276869] usbcore: registered new device driver usb
[ 0.282522] workqueue: max_active 576 requested for napi_workq is out of range, clamping between 1 and 512
[ 0.294467] clocksource: Switched to clocksource MIPS
--
[ 0.708199] NET: Registered protocol family 10
[ 0.715876] Segment Routing with IPv6
[ 0.718218] NET: Registered protocol family 17
[ 0.722769] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
[ 0.735555] 8021q: 802.1Q VLAN Support v1.8
[ 0.746142] pcie-xrx200 1d900000.pcie: failed to get the PCIe PHY
[ 0.859313] libphy: lantiq,xrx200-mdio: probed
[ 0.869051] net-xrx200: invalid MAC, using random
[ 0.872575] Atheros 8030 ethernet 0:00: attached PHY driver [Atheros 8030 ethernet] (mii_bus:phy_addr=0:00, irq=POLL)
[ 0.883256] Atheros 8030 ethernet 0:01: attached PHY driver [Atheros 8030 ethernet] (mii_bus:phy_addr=0:01, irq=POLL)
[ 0.894242] Intel XWAY PHY11G (xRX v1.2 integrated) 0:11: attached PHY driver [Intel XWAY PHY11G (xRX v1.2 integrated)] (mii_bus:phy_addr=0:11, irq=POLL)
[ 0.907971] Intel XWAY PHY11G (xRX v1.2 integrated) 0:13: attached PHY driver [Intel XWAY PHY11G (xRX v1.2 integrated)] (mii_bus:phy_addr=0:13, irq=POLL)
[ 1.046546] PCI host bridge /fpi@10000000/pcie@d900000 ranges:
[ 1.051221] PCI host bridge to bus 0000:00
[ 1.055083] pci_bus 0000:00: root bus resource [mem 0x1c000000-0x1cffffff]
[ 1.061969] pci_bus 0000:00: root bus resource [io 0x1d800000-0x1d8fffff]
[ 1.068840] pci_bus 0000:00: root bus resource [??? 0x00000000 flags 0x0]
Notably might be the line ”failed to get the PCIe PHY“ which does not appear in 19.07.7.