Re: [net-next PATCH 1/3] net: phy: extend PHY package API to support multiple global address

From: Christian Marangi
Date: Sun Nov 26 2023 - 13:07:42 EST


On Sun, Nov 26, 2023 at 07:04:26PM +0100, Andrew Lunn wrote:
> > @@ -1648,20 +1648,27 @@ EXPORT_SYMBOL_GPL(phy_driver_is_genphy_10g);
> > /**
> > * phy_package_join - join a common PHY group
> > * @phydev: target phy_device struct
> > - * @addr: cookie and PHY address for global register access
> > + * @base_addr: cookie and base PHY address of PHY package for offset
> > + * calculation of global register access
> > * @priv_size: if non-zero allocate this amount of bytes for private data
> > *
> > * This joins a PHY group and provides a shared storage for all phydevs in
> > * this group. This is intended to be used for packages which contain
> > * more than one PHY, for example a quad PHY transceiver.
> > *
> > - * The addr parameter serves as a cookie which has to have the same value
> > - * for all members of one group and as a PHY address to access generic
> > - * registers of a PHY package. Usually, one of the PHY addresses of the
> > - * different PHYs in the package provides access to these global registers.
> > + * The addr parameter serves as cookie which has to have the same values
>
> addr has been renamed base_addr.
>
> > + * for all members of one group and as the base PHY address of the PHY package
> > + * for offset calculation to access generic registers of a PHY package.
> > + * Usually, one of the PHY addresses of the different PHYs in the package
> > + * provides access to these global registers.
> > * The address which is given here, will be used in the phy_package_read()
> > - * and phy_package_write() convenience functions. If your PHY doesn't have
> > - * global registers you can just pick any of the PHY addresses.
> > + * and phy_package_write() convenience functions as base and added to the
> > + * passed offset in those functions. If your PHY doesn't have global registers
> > + * you can just pick any of the PHY addresses.
>
>
> I would not add this last sentence. We want a clearly defined meaning
> of base_addr. Its the lowest address in the package. It does not
> matter if its not used, it should still be the lowest address in the
> package.
>
> > + * In some special PHY package, multiple PHY are used for global init of
>
> I don't see why they are special.
>
> > -static inline int phy_package_read(struct phy_device *phydev, u32 regnum)
> > +static inline int phy_package_read(struct phy_device *phydev,
> > + unsigned int addr_offset, u32 regnum)
> > {
> > struct phy_package_shared *shared = phydev->shared;
> > + int addr;
> >
> > - if (!shared)
> > + if (!shared || shared->base_addr + addr_offset > PHY_MAX_ADDR)
> > return -EIO;
> >
> > - return mdiobus_read(phydev->mdio.bus, shared->addr, regnum);
> > + addr = shared->base_addr + addr_offset;
> > + return mdiobus_read(phydev->mdio.bus, addr, regnum);
>
> This might be a little bit more readable:
>
> static inline int phy_package_read(struct phy_device *phydev,
> unsigned int addr_offset, u32 regnum)
> {
> struct phy_package_shared *shared = phydev->shared;
> int addr = shared->base_addr + addr_offset;

Isn't this problematic if shared is NULL?

I can add 2 if condition and set addr in between only after shared not
NULL check is done?

>
> if (!shared)
> if (!shared || addr > PHY_MAX_ADDR)
> return -EIO;
>
> return mdiobus_read(phydev->mdio.bus, addr, regnum);
> }
>
>

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