Re: [PATCH] arm64: dts: renesas: white-hawk-cpu: Move avb0 reset gpio to mdio node

[Marek Vasut <marex@denx.de>]

On 10/22/24 9:38 AM, Geert Uytterhoeven wrote:
> Hi Marek,

Hello Geert,

>>>> I was hoping Geert would comment on this first, but seems like maybe no.
>>>> I think, since the PHY node does have a compatible string AND the reset
>>>> is connected to the PHY, I would keep the reset property in the PHY
>>>> node. Sorry.
>>>
>>> You are inverting the reasoning ;-) The compatible strings were added
>>> because otherwise the PHY core can not identify the PHY when the
>>> reset is asserted (e.g. after kexec).
>>
>> ... or because the PHY requires some complex sequence to bring it up, it
>> is not just reset.
> 
> That is your hypothetical case, but not the reason behind commit
> 722d55f3a9bd810f ("arm64: dts: renesas: Add compatible properties to
> KSZ9031 Ethernet PHYs").

We can stick to the "reset line in unknown state" here for the sake of 
this argument, it makes no difference.

>>> If possible, I'd rather remove
>>> the compatible strings again, as different PHYs may be mounted on
>>> different PHY revisions, causing a headache for DTB management.
>>
>> Will that ever be the case with this hardware ?
> 
> Dunno. It did happen with the Beacon boards.

Let's cross that bridge when we come to it ?

>>> So, what would you suggest when the PHY nodes would not have compatible
>>> strings?
>> I would suggest keep the PHY compatible strings, because that is the
>> most accurate method to describe the hardware and fulfill the PHY bring
>> up requirements. If the PHY changes on this hardware in some future
> 
> That issue is moot for KSZ9031.

If the PHY won't change, then we can keep the compatible strings ?

>> revision, we can revisit this discussion ? Maybe bootloader-applied DTOs
>> could work then ?
> 
> So, what would you suggest when the PHY nodes would not have compatible
> strings?
I hope I already answered that question before.

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