netdev - Re: [PATCH net-next v3 8/8] Revert "net: dsa: OF-ware slave_mii

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Date: Mon, 8 Jan 2024 12:48:30 +0300
From: Arınç ÜNAL <arinc.unal@...nc9.com>
To: Luiz Angelo Daros de Luca <luizluca@...il.com>
Cc: netdev@...r.kernel.org, linus.walleij@...aro.org, alsi@...g-olufsen.dk,
 andrew@...n.ch, f.fainelli@...il.com, olteanv@...il.com,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Subject: Re: [PATCH net-next v3 8/8] Revert "net: dsa: OF-ware slave_mii_bus"

On 8.01.2024 07:44, Luiz Angelo Daros de Luca wrote:
> Hi Arinç,
> 
>> It looks like this patch will cause the MDIO bus of the switches probed on
>> OF which are controlled by these subdrivers to only be registered
>> non-OF-based.
>>
>> drivers/net/dsa/b53/b53_common.c
>> drivers/net/dsa/lan9303-core.c
>> drivers/net/dsa/vitesse-vsc73xx-core.c
>>
>> These subdrivers let the DSA driver register the bus OF-based or
>> non-OF-based:
>> - ds->ops->phy_read() and ds->ops->phy_write() are present.
>> - ds->user_mii_bus is not populated.
> 
> I checked the changes on those drivers since
> fe7324b932222574a0721b80e72c6c5fe57960d1 and nothing indicates that
> they were changing anything related to the user mii bus. I also
> checked bindings for the mdio node requirement. None of them mentioned
> the mdio node.

Ok, we need to specifically mention the latter on the patch log.

> 
>> Not being able to register the bus OF-based may cause issues. There is an
>> example for the switch on the MT7988 SoC which is controlled by the MT7530
>> DSA subdriver. Being able to reference the PHYs on the switch MDIO bus is
>> mandatory on MT7988 as calibration data from NVMEM for each PHY is
>> required.
>>
>> I suggest that we hold off on this patch until these subdrivers are made to
>> be capable of registering the MDIO bus as OF-based on their own.
> 
> We might be over cautious keeping this for more time after the realtek
> refactoring gets merged. The using OF with the generic user mii bus
> driver is just a broken design and probably not in use. Anyway, it is
> not a requirement for the series. If there is no objection, I can drop
> it.

Sounds good to me. I'd like to take this patch off your hands.

> 
> I would like to send v4 with the OF node handling simplified by the
> change in the MDIO API. However, I'm reluctant to send mostly the same
> code without any reviews.

I suppose our conversation here will remind Vladimir and Alvin to review.

Arınç