Hi Marek,
On Mon, Oct 21, 2024 at 2:13 AM Marek Vasut <marex@xxxxxxx> wrote:
> On 10/15/24 4:48 PM, Niklas Söderlund wrote:
> >>> However, the reset signal may be in asserted state when the PHY is
> >>> probed (e.g. after unbind from the Ethernet driver, or during kexec).
> >>> Identifying the PHY by reading the ID register requires deasserting
> >>> the reset first.
> >> That may not be the entire precondition. For example the SMSC LAN87xx PHYs
> >> also require PHY clock to be enabled before the reset is toggled, but such
> >> information is available only to the specific PHY driver.
> >>
> >> The MDIO-level reset GPIO handling, as far as I understand it, applies in
> >> case there are more PHYs on the MDIO bus which share the same reset GPIO
> >> line.
> >>
> >> In this case there is only one PHY on the MDIO bus, so the only bit which
> >> applies is the potential PHY-specific reset requirement handling. If the PHY
> >> driver ever gets extended with such a thing in the future, then having the
> >> reset-gpios in the PHY node is beneficial over having it in MDIO node.
> >>
> >> It will always be a compromise between the above and best-effort PHY
> >> auto-detection though.
> >
> > I agree this is not needed if the PHY is identified by the compatible
> > string, but might be if it is not. In this case it works and the reason
> > for this patch was just to align the style used here.
> >
> > I'm happy to drop this patch, or send a rebased version that applies
> > since the context changed ;-) Marek, Geert what is your view? I'm happy
> > with either option.
>
> 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). 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.
So, what would you suggest when the PHY nodes would not have compatible
strings?
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
