Re: [PATCH net-next v3 07/11] net: phy: introduce phy_mdiobus_read_mmd()

[Andrew Lunn]

> +static int __phy_mdiobus_read_mmd(struct mii_bus *bus, int phy_addr,
> +				  enum phy_access_mode access_mode,
> +				  int devad, u32 regnum)
> +{
> +	switch (access_mode) {
> +	case PHY_ACCESS_C45:
> +		return __mdiobus_c45_read(bus, phy_addr, devad, regnum);
> +	case PHY_ACCESS_C22:
> +		/* ignore return value for legacy reasons */
> +		mmd_phy_indirect(bus, phy_addr, devad, regnum, false);
> +
> +		/* Read the content of the MMD's selected register */
> +		return __mdiobus_read(bus, phy_addr, MII_MMD_DATA);
> +	default:
> +		return -EOPNOTSUPP;
> +	}

So this is reading a C45 register space register, otherwise it would
not be called _mmd and have a devad. So access_mode should really be
transfer mode. Until now, only transfer mode C45 can be used to access
C45 register space. The point of this patchset is to add a new
C45_OVER_C22 transfer mode.

And C22 would should give -EINVAL, since you cannot use plain C22 bus
transactions to access C45 register space.

	Andrew