netdev - Re: [PATCH] net: mdio: of: Do not treat fixed-link as PHY

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Date:   Mon, 30 Mar 2020 10:22:28 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Codrin Ciubotariu <codrin.ciubotariu@...rochip.com>
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, hkallweit1@...il.com,
        linux@...linux.org.uk, davem@...emloft.net
Subject: Re: [PATCH] net: mdio: of: Do not treat fixed-link as PHY



On 3/30/2020 9:30 AM, Andrew Lunn wrote:
> On Mon, Mar 30, 2020 at 07:01:36PM +0300, Codrin Ciubotariu wrote:
>> Some ethernet controllers, such as cadence's macb, have an embedded MDIO.
>> For this reason, the ethernet PHY nodes are not under an MDIO bus, but
>> directly under the ethernet node. Since these drivers might use
>> of_mdiobus_child_is_phy(), we should fix this function by returning false
>> if a fixed-link is found.
> 
> So i assume the problem occurs here:
> 
> static int macb_mdiobus_register(struct macb *bp)
> {
>         struct device_node *child, *np = bp->pdev->dev.of_node;
> 
>         /* Only create the PHY from the device tree if at least one PHY is
>          * described. Otherwise scan the entire MDIO bus. We do this to support
>          * old device tree that did not follow the best practices and did not
>          * describe their network PHYs.
>          */
>         for_each_available_child_of_node(np, child)
>                 if (of_mdiobus_child_is_phy(child)) {
>                         /* The loop increments the child refcount,
>                          * decrement it before returning.
>                          */
>                         of_node_put(child);
> 
>                         return of_mdiobus_register(bp->mii_bus, np);
>                 }
> 
>         return mdiobus_register(bp->mii_bus);
> }
> 
> I think a better solution is
> 
>         for_each_available_child_of_node(np, child)
> +		if (of_phy_is_fixed_link(child)
> +		   continue;
>                 if (of_mdiobus_child_is_phy(child)) {
>                         /* The loop increments the child refcount,
>                          * decrement it before returning.
>                          */
>                         of_node_put(child);
> 
>                         return of_mdiobus_register(bp->mii_bus, np);
>                 }
> 
>         return mdiobus_register(bp->mii_bus);
> }
> 
> This problem is only an issue for macb, so keep the fix local to macb.

Agree, there is no reason for of_mdiobus_child_is_phy() to be checking
for a fixed-link. If you submit this formally:

Acked-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian