Hi,

Am Samstag, 28. Februar 2026, 04:52:01 CET schrieb Wei Fang:

quoted

quoted

+static int imx95_enetc_mdio_phyaddr_config(struct platform_device
+*pdev) {
+	struct netc_blk_ctrl *priv = platform_get_drvdata(pdev);
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	int bus_devfn, addr, err;
+	u32 phy_mask = 0;
+
+	err = netc_get_emdio_phy_mask(np, &phy_mask);
+	if (err) {
+		dev_err(dev, "Failed to get PHY address mask\n");
+		return err;
+	}
+
+	/* Update the port EMDIO PHY address through parsing phy properties.
+	 * This is needed when using the port EMDIO but it's harmless when
+	 * using the central EMDIO. So apply it on all cases.
+	 */
+	for_each_child_of_node_scoped(np, child) {
+		for_each_child_of_node_scoped(child, gchild) {
+			if (!of_device_is_compatible(gchild, "pci1131,e101"))
+				continue;
+
+			bus_devfn = netc_of_pci_get_bus_devfn(gchild);
+			if (bus_devfn < 0) {
+				dev_err(dev, "Failed to get BDF number\n");
+				return bus_devfn;
+			}
+
+			addr = netc_get_phy_addr(gchild);
+			if (addr < 0) {
+				dev_err(dev, "Failed to get PHY address\n");
+				return addr;
+			}
+
+			if (phy_mask & BIT(addr)) {

... which will break here if there is an Ethernet PHY using address 0 in
'netc_emdio' node.
See arch/arm64/boot/dts/freescale/imx95-tqma9596sa.dtsi node
ethernet-phy@0.

AFAIU, the PHY address 0 is a special address, below is the description of
PHYAD from IEEE 802.3 Clause 22.

A PHY that is connected to the station management entity via the
mechanical interface defined in 22.6 shall always respond to transactions
addressed to PHY Address zero <00000>. A station management entity
that is attached to multiple PHYs must have prior knowledge of the 
appropriate PHY Address for each PHY.

Therefore, for most PHYs, PHY address 0 is typically used as the broadcast
address or default response address. In designs that control multiple PHYs
via EMDIO, it is recommended to avoid setting a specific PHY to address 0
to prevent bus conflicts.

I know about this special meaning, but there are hardware design which do not
take this into account.

If the PHY on your board does not use PHY address 0 as the broadcast address
or the default response address, then we should check the PHY address first and
then check the phy_mask in imx95_enetc_mdio_phyaddr_config(), just the same
as imx94_enetc_mdio_phyaddr_config().

I'm not sure if this is the right fix. What about the case where phy_mask is
supposed to be 0, because there are no PHY subnodes of netc_emdio. Instead
the PHY with address is a subnode of the enet_portX is supposed to have
netc_get_phy_addr() return 0 because that's the actual address. But with
the current flow from imx94_enetc_mdio_phyaddr_config() and your suggestion
for i.MX95 case we erroneously skip that node.

Best regards,
Alexander
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