Re: racing ndo_open()/phylink*connect() with phy_probe()

Andrew Lunn
2024-05-01T15:08:02Z

On Tue, Apr 30, 2024 at 04:02:19PM -0500, Andrew Halaney wrote:
> Hi,
>
> I've been taking a look at the following error message:
>
> qcom-ethqos 23000000.ethernet end1: __stmmac_open: Cannot attach to PHY (error: -19)
>
> end1 is using a phy on the mdio bus of end0, not on its own bus. Something
> like this devicetree snippet highlights the relationship:
>
> // end0
> &ethernet0 {
> phy-mode = "sgmii";
> phy-handle = <&sgmii_phy0>;
>
> mdio {
> compatible = "snps,dwmac-mdio";
> sgmii_phy0: phy@8 {
> compatible = "ethernet-phy-id0141.0dd4";
> reg = <0x8>;
> device_type = "ethernet-phy";
> };
>
> sgmii_phy1: phy@a {
> compatible = "ethernet-phy-id0141.0dd4";
> reg = <0xa>;
> device_type = "ethernet-phy";
> };
> };
> };
>
> // end1
> &ethernet1 {
> phy-mode = "sgmii";
> phy-handle = <&sgmii_phy1>;
> };

I agree with Russell here. You need to determine where the ENODEV
comes from.

It seems unlikely, but one possibility is:

static int stmmac_xgmac2_mdio_read_c22(struct mii_bus *bus, int phyaddr,
int phyreg)
{
struct net_device *ndev = bus->priv;
struct stmmac_priv *priv;
u32 addr;

priv = netdev_priv(ndev);

/* Until ver 2.20 XGMAC does not support C22 addr >= 4 */
if (priv->synopsys_id < DWXGMAC_CORE_2_20 &&
phyaddr > MII_XGMAC_MAX_C22ADDR)
return -ENODEV;

Maybe if the interface is down, priv->synopsys_id has not been set
yet? Your devices are at address 8 and 10, so if priv->synopsys_id
where 0, this would give you the ENODEV.

Once you know the root cause, we might be able to make suggests how to
fix it.

Andrew