Re: [PATCH net-next 3/4] net: phy: smsc: fix and improve WoL support

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Mon, Jul 21, 2025 at 01:14:45PM +0200, Gatien Chevallier wrote:
> +static int smsc_phy_suspend(struct phy_device *phydev)
> +{
> +	if (!phydev->wol_enabled)
> +		return genphy_suspend(phydev);

This should not be necessary. Take a look at phy_suspend(). Notice:

        phydev->wol_enabled = phy_drv_wol_enabled(phydev) ||
                              (netdev && netdev->ethtool->wol_enabled);
        /* If the device has WOL enabled, we cannot suspend the PHY */
        if (phydev->wol_enabled && !(phydrv->flags & PHY_ALWAYS_CALL_SUSPEND))
                return -EBUSY;

PHY_ALWAYS_CALL_SUSPEND is not set for this PHY, therefore if
phydev->wol_enabled is set by the above code, phydrv->suspend will
not be called.

> +
> +	return 0;
> +}
> +
> +static int smsc_phy_resume(struct phy_device *phydev)
> +{
> +	int rc;
> +
> +	if (!phydev->wol_enabled)
> +		return genphy_resume(phydev);
> +
> +	rc = phy_read_mmd(phydev, MDIO_MMD_PCS, MII_LAN874X_PHY_MMD_WOL_WUCSR);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (!(rc & MII_LAN874X_PHY_WOL_STATUS_MASK))
> +		return 0;
> +
> +	dev_info(&phydev->mdio.dev, "Woke up from LAN event.\n");
> +	rc = phy_write_mmd(phydev, MDIO_MMD_PCS, MII_LAN874X_PHY_MMD_WOL_WUCSR,
> +			   rc | MII_LAN874X_PHY_WOL_STATUS_MASK);
> +
> +	return rc;

Note that this will be called multiple times, e.g. during attachment of
the PHY to the network device, when the device is opened, etc even
without ->suspend having been called, and before ->wol_enabled has
been set. Make sure your code is safe for this.

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