linux-kernel - Re: [PATCH] net: phy: marvell: fix detection of PHY on Topaz switches

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Message-ID: <YHRH2zWsYkv/yjYz@lunn.ch>
Date:   Mon, 12 Apr 2021 15:15:07 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Pali Rohár <pali@...nel.org>
Cc:     Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Marek Behún <kabel@...nel.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: marvell: fix detection of PHY on Topaz switches

> +static u16 mv88e6xxx_physid_for_family(enum mv88e6xxx_family family);
> +

No forward declaration please. Move the code around. It is often best
to do that in a patch which just moves code, no other changes. It
makes it easier to review.

>  static int mv88e6xxx_mdio_read(struct mii_bus *bus, int phy, int reg)
>  {
>  	struct mv88e6xxx_mdio_bus *mdio_bus = bus->priv;
> @@ -3040,24 +3042,9 @@ static int mv88e6xxx_mdio_read(struct mii_bus *bus, int phy, int reg)
>  	err = chip->info->ops->phy_read(chip, bus, phy, reg, &val);
>  	mv88e6xxx_reg_unlock(chip);
>  
> -	if (reg == MII_PHYSID2) {
> -		/* Some internal PHYs don't have a model number. */
> -		if (chip->info->family != MV88E6XXX_FAMILY_6165)
> -			/* Then there is the 6165 family. It gets is
> -			 * PHYs correct. But it can also have two
> -			 * SERDES interfaces in the PHY address
> -			 * space. And these don't have a model
> -			 * number. But they are not PHYs, so we don't
> -			 * want to give them something a PHY driver
> -			 * will recognise.
> -			 *
> -			 * Use the mv88e6390 family model number
> -			 * instead, for anything which really could be
> -			 * a PHY,
> -			 */
> -			if (!(val & 0x3f0))
> -				val |= MV88E6XXX_PORT_SWITCH_ID_PROD_6390 >> 4;
> -	}
> +	/* Some internal PHYs don't have a model number. */
> +	if (reg == MII_PHYSID2 && !(val & 0x3f0))
> +		val |= mv88e6xxx_physid_for_family(chip->info->family);
>  
>  	return err ? err : val;
>  }
> @@ -5244,6 +5231,39 @@ static const struct mv88e6xxx_info *mv88e6xxx_lookup_info(unsigned int prod_num)
>  	return NULL;
>  }
>  
> +/* This table contains representative model for every family */
> +static const enum mv88e6xxx_model family_model_table[] = {
> +	[MV88E6XXX_FAMILY_6095] = MV88E6095,
> +	[MV88E6XXX_FAMILY_6097] = MV88E6097,
> +	[MV88E6XXX_FAMILY_6185] = MV88E6185,
> +	[MV88E6XXX_FAMILY_6250] = MV88E6250,
> +	[MV88E6XXX_FAMILY_6320] = MV88E6320,
> +	[MV88E6XXX_FAMILY_6341] = MV88E6341,
> +	[MV88E6XXX_FAMILY_6351] = MV88E6351,
> +	[MV88E6XXX_FAMILY_6352] = MV88E6352,
> +	[MV88E6XXX_FAMILY_6390] = MV88E6390,
> +};

This table is wrong. MV88E6390 does not equal
MV88E6XXX_PORT_SWITCH_ID_PROD_6390. MV88E6XXX_PORT_SWITCH_ID_PROD_6390
was chosen because it is already an MDIO device ID, in register 2 and
3. It probably will never clash with a real Marvell PHY ID. MV88E6390
is just a small integer, and there is a danger it will clash with a
real PHY.

> --- a/drivers/net/phy/marvell.c
> +++ b/drivers/net/phy/marvell.c
> @@ -3021,9 +3021,34 @@ static struct phy_driver marvell_drivers[] = {
>  		.get_stats = marvell_get_stats,
>  	},
>  	{
> -		.phy_id = MARVELL_PHY_ID_88E6390,
> +		.phy_id = MARVELL_PHY_ID_88E6341_FAMILY,
>  		.phy_id_mask = MARVELL_PHY_ID_MASK,
> -		.name = "Marvell 88E6390",
> +		.name = "Marvell 88E6341 Family",

You cannot just replace the MARVELL_PHY_ID_88E6390. That will break
the 6390! You need to add the new PHY for the 88E6341.

    Andrew