[PATCH v3 0/2] riscv: dts: sophgo: Milk-V Duo 256M ethernet support

[PATCH v3 0/2] riscv: dts: sophgo: Milk-V Duo 256M ethernet support

[Chen-Yu Yeh]

The Milk-V Duo 256M has no Ethernet connector of its own; the SG2002's
internal PHY is only usable through the optional USB & Ethernet IO
board. This series adds an overlay for that board and fixes the name of
the internal PHY node it exposes.

Changes in v3:
 - Rename the PHY node to ethernet-phy@1, as the commit message already
   said; v2 only changed the unit address (sashiko-bot). dtbs_check now
   validates the node against ethernet-phy.yaml, with no new warnings.
 - Drop the blank line in the trailer block of 2/2 (Hiago)
 - Collect Hiago's Reviewed-by
 - Keep Inochi's Reviewed-by on 2/2, since the only change is the node
   name

Changes in v2:
 - Enable Ethernet through an overlay instead of in the board
   devicetree, since without the IO board the pins may be used as GPIO
   (Inochi)
 - Send both patches in one thread (Inochi)
 - Test link-up and traffic on the IO board, which v1 could not
 - Collect Inochi's Reviewed-by on the PHY node name fix

The overlay has the same shape as Hiago's for the Milk-V Duo [1], so the
two boards stay consistent. The PHY node name fix is in cv180x.dtsi and
so covers that board as well.

Testing, with a kernel built from this branch:

 - sg2002-milkv-duo256m-eth.dtb: eth0 comes up at 100Mbps/Full, gets an
   address via DHCP and passes traffic
 - sg2002-milkv-duo256m.dtb: no eth0 is created, and the gmac node
   reads back as disabled
   
Kernel log with sg2002-milkv-duo256m-eth.dtb:

  [    1.426499] stmmaceth 4070000.ethernet: User ID: 0x10, Synopsys ID: 0x37
  [    1.426536] stmmaceth 4070000.ethernet: 	DWMAC1000
  [    6.052829] stmmaceth 4070000.ethernet eth0: PHY [mdio_mux-0.0:01] driver [Generic PHY] (irq=POLL)
  [    8.138131] stmmaceth 4070000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx

  # ip addr show eth0
  2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
      inet 192.168.0.47/24 brd 192.168.0.255 scope global dynamic noprefixroute eth0

With the base sg2002-milkv-duo256m.dtb:

  # ip addr show eth0
  ip: can't find device 'eth0'
  # cat /proc/device-tree/soc/ethernet@4070000/status
  disabled

iperf3 against a desktop on the same switch gives 94 Mbit/s with the
board sending and 70-74 Mbit/s with it receiving, with no
retransmissions either way. The receive side being slower is not a CPU
limit on the board; I have not looked into it further yet.

v1: https://lore.kernel.org/sophgo/20260803163323.74414-1-chenyou910331@gmail.com/
    https://lore.kernel.org/sophgo/20260803163427.74445-1-chenyou910331@gmail.com/

v2: https://lore.kernel.org/sophgo/20261003084627.353899-1-chenyou910331@gmail.com/

[1] https://lore.kernel.org/sophgo/20261001-milkv-duo-eth-overlay-v1-1-78bc1454f35b@baylibre.com/


Chen-Yu Yeh (2):
  riscv: dts: sophgo: add Milk-V Duo 256M ethernet support overlay
  riscv: dts: sophgo: cv180x: Fix internal ephy node name

 arch/riscv/boot/dts/sophgo/Makefile             |  3 +++
 arch/riscv/boot/dts/sophgo/cv180x.dtsi          |  2 +-
 .../dts/sophgo/sg2002-milkv-duo256m-eth.dtso    | 17 +++++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m-eth.dtso

-- 
2.43.0

[PATCH v3 1/2] riscv: dts: sophgo: add Milk-V Duo 256M ethernet support overlay

[Chen-Yu Yeh]

The SG2002 has an internal 10/100 Ethernet PHY, but on the Milk-V Duo
256M the Ethernet signals only reach the RJ45 connector on the optional
USB & Ethernet IO board. The MAC (gmac0) and the MDIO multiplexer used
to reach the internal PHY are already described in cv180x.dtsi but are
disabled, and they cannot be enabled in the board devicetree because
without the IO board the same pins may be used as GPIO.

Add an overlay that enables them.

Tested on Milk-V Duo 256M with the USB & Ethernet IO board: the link
comes up at 100Mbps/Full, the interface gets an address via DHCP and
passes traffic in both directions. Without the overlay, eth0 does not
appear.

Reviewed-by: Hiago De Franco <hfranco@baylibre.com>
Signed-off-by: Chen-Yu Yeh <chenyou910331@gmail.com>
---
 arch/riscv/boot/dts/sophgo/Makefile             |  3 +++
 .../dts/sophgo/sg2002-milkv-duo256m-eth.dtso    | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m-eth.dtso

diff --git a/arch/riscv/boot/dts/sophgo/Makefile b/arch/riscv/boot/dts/sophgo/Makefile
index d5c80d4ff005..49639cb0888b 100644
--- a/arch/riscv/boot/dts/sophgo/Makefile
+++ b/arch/riscv/boot/dts/sophgo/Makefile
@@ -4,6 +4,9 @@ dtb-$(CONFIG_ARCH_SOPHGO) += cv1812h-huashan-pi.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2000-milkv-duo-s.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2002-licheerv-nano-b.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2002-milkv-duo256m.dtb
+sg2002-milkv-duo256m-eth-dtbs := sg2002-milkv-duo256m.dtb sg2002-milkv-duo256m-eth.dtbo
+dtb-$(CONFIG_ARCH_SOPHGO) += sg2002-milkv-duo256m-eth.dtb
+dtb-$(CONFIG_ARCH_SOPHGO) += sg2002-milkv-duo256m-eth.dtbo
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2042-milkv-pioneer.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2042-evb-v1.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2042-evb-v2.dtb
diff --git a/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m-eth.dtso b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m-eth.dtso
new file mode 100644
index 000000000000..cc93746d932c
--- /dev/null
+++ b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m-eth.dtso
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Enable ethernet on Milk-V Duo 256M with the USB & Ethernet IO board.
+ *
+ * Copyright (c) 2026, Chen-Yu Yeh <chenyou910331@gmail.com>
+ */
+
+/dts-v1/;
+/plugin/;
+
+&gmac0 {
+	status = "okay";
+};
+
+&mdio {
+	status = "okay";
+};
-- 
2.43.0

[PATCH v3 2/2] riscv: dts: sophgo: cv180x: Fix internal ephy node name

[Chen-Yu Yeh]

The internal EPHY node is named "phy@0" while its reg property is <1>.
The unit-address should match the first entry of the reg property, but
this is not checked by dtc for MDIO buses. The kernel confirms the PHY
is indeed at address 1:

  eth0: PHY [mdio_mux-0.0:01] driver [Generic PHY]

Rename the node to ethernet-phy@1, which also follows the common naming
convention for ethernet PHY nodes.

Fixes: ba1abacc57cb ("riscv: dts: sophgo: Add mdio multiplexer device for cv18xx")
Reviewed-by: Inochi Amaoto <inochiama@gmail.com>
Reviewed-by: Hiago De Franco <hfranco@baylibre.com>
Signed-off-by: Chen-Yu Yeh <chenyou910331@gmail.com>
---
 arch/riscv/boot/dts/sophgo/cv180x.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/boot/dts/sophgo/cv180x.dtsi b/arch/riscv/boot/dts/sophgo/cv180x.dtsi
index ec3bf305274a..d2ec70fd515e 100644
--- a/arch/riscv/boot/dts/sophgo/cv180x.dtsi
+++ b/arch/riscv/boot/dts/sophgo/cv180x.dtsi
@@ -71,7 +71,7 @@ internal_mdio: mdio@0 {
 				#size-cells = <0>;
 				reg = <0>;
 
-				internal_ephy: phy@0 {
+				internal_ephy: ethernet-phy@1 {
 					compatible = "ethernet-phy-ieee802.3-c22";
 					reg = <1>;
 				};
-- 
2.43.0