linux-kernel - Re: [PATCH net-next v2 3/7] net: macb: parse PHY nodes found under an MDIO node

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Message-ID: <c3946f5b-d0ef-b64f-6882-9d44751a983b@microchip.com>
Date:   Fri, 24 Jul 2020 07:28:39 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <f.fainelli@...il.com>, <Codrin.Ciubotariu@...rochip.com>,
        <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <Nicolas.Ferre@...rochip.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <andrew@...n.ch>, <robh+dt@...nel.org>,
        <alexandre.belloni@...tlin.com>, <Ludovic.Desroches@...rochip.com>
Subject: Re: [PATCH net-next v2 3/7] net: macb: parse PHY nodes found under an
 MDIO node



On 23.07.2020 21:59, Florian Fainelli wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 7/21/20 10:13 AM, Codrin Ciubotariu wrote:
>> The MACB embeds an MDIO bus controller. For this reason, the PHY nodes
>> were represented as sub-nodes in the MACB node. Generally, the
>> Ethernet controller is different than the MDIO controller, so the PHYs
>> are probed by a separate MDIO driver. Since adding the PHY nodes directly
>> under the ETH node became deprecated, we adjust the MACB driver to look
>> for an MDIO node and register the subnode MDIO devices.
>>
>> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@...rochip.com>
>> ---
>>
>> Changes in v2:
>>  - readded newline removed by mistake;
>>
>>  drivers/net/ethernet/cadence/macb_main.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
>> index 89fe7af5e408..b25c64b45148 100644
>> --- a/drivers/net/ethernet/cadence/macb_main.c
>> +++ b/drivers/net/ethernet/cadence/macb_main.c
>> @@ -740,10 +740,20 @@ static int macb_mii_probe(struct net_device *dev)
>>  static int macb_mdiobus_register(struct macb *bp)
>>  {
>>       struct device_node *child, *np = bp->pdev->dev.of_node;
>> +     struct device_node *mdio_node;
>> +     int ret;
>>
>>       if (of_phy_is_fixed_link(np))
>>               return mdiobus_register(bp->mii_bus);
> 
> Does not this need changing as well? Consider the use case of having
> your MACB Ethernet node have a fixed-link property to describe how it
> connects to a switch, and your MACB MDIO controller, expressed as a
> sub-node, describing the MDIO attached switch it connects to.

Just asking, does this worth having/changing it as long as there is no in
kernel board/configuration that could benefit off?

Thank you,
Claudiu Beznea

> 
>>
>> +     /* if an MDIO node is present, it should contain the PHY nodes */
>> +     mdio_node = of_get_child_by_name(np, "mdio");
>> +     if (mdio_node) {
>> +             ret = of_mdiobus_register(bp->mii_bus, mdio_node);
>> +             of_node_put(mdio_node);
>> +             return ret;
>> +     }
>> +
>>       /* 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
>>
> 
> 
> --
> Florian
>