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

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Marek,

On Sun, Oct 27, 2024 at 5:09 PM Marek Vasut <marex@denx.de> wrote:
> On 10/22/24 9:38 AM, Geert Uytterhoeven wrote:
> >>>> 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 ?

Sorry for being unclear. I should have written "the PHY bring-up
requirements are moot for KSZ9031".

> >> 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.

Sorry, I may have missed that?

I really prefer not having the PHY compatible strings, as DT should
describe only what cannot be auto-detected.

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds