Re: [RFC 3/5] dt-bindings: power: Add binding for MediaTek MT7988 topmisc power controller

[AngeloGioacchino Del Regno]

Il 15/04/25 16:03, Frank Wunderlich ha scritto:
> Am 15. April 2025 11:59:06 MESZ schrieb AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>:
> > Il 15/04/25 11:52, Frank Wunderlich ha scritto:
> > > Hi Angelo,
> > >
> > > Am 14. April 2025 12:25:23 MESZ schrieb AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>:
> > > > Il 13/04/25 10:58, Frank Wunderlich ha scritto:
> > > > > From: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
> > > > >
> > > > > Topmisc is a systemcontroller used for xs-phy and ethernet on  mt7988.
> > > > > Add binding for it.
> > > >
> > > > That's the wrong binding... check mfd/syscon.yaml :-)
> > > >
> > > > P.S.: Is there any reset controller in topmisc? Any clock?
> > > >        If yes, syscon.yaml is also wrong, and you need a driver for that.
> > > >        Remember: If it turns out *later* that this has clk/resets and the
> > > >        bindings are already set for just a syscon, it's gonna be way harder!
> > > >
> > > > Cheers,
> > > > Angelo
> > >
> > > Ok based on the power-domain-cells property i guessed powercontroller is the right place.
> >
> > power-domain-cells, but without any power domain assignment, so that was wrong :)))
> >
> > > But based on your suggestion i tried moving compatible to syscon binding and made dtbs_check here.
> > >
> > > I can confirm dropping the unexpected properties reported by syscon binding (power-domain-cells,clock-cells,adress-cells and size-cells) are not needed for function (xsphy and ethernet).
> > >
> > > For verifying that there are really no clocks/resets in topmisc (have not found it in public available register documents) i asked mtk (waiting for answer).
> > >
> > > Also got it working without the syscon compatible by changing ethernet driver too (after this change xsphy was also working).
> >
> > Perfect, a bit of a cleanup and you're done, then!
> >
> > Cheers!
> >
> > > Eth:
> > > https://github.com/frank-w/BPI-Router-Linux/commit/d866e648717800b6f6395ad36c38f9effcf0498d
> > > Xsphy:
> > > <https://github.com/frank-w/BPI-Router-Linux/commit/0121a94df99700487704ca056b210b13db07e90c>
> > >
> > > regards Frank
>
> Got response from MTK and basicly topmisc contains a powercontroller (for cpu and internal 2g5) but currently not needed because ATF already switch this on. The second part is the pcs/phy muxing and 3rd some unneeded switches (where i have no detailed information). But no clocks or resets as these are handled in the connected platform driver (xsphy/ethernet).
>
> So my original binding imho made more sense.
>
> The syscon binding seems to need syscon fallback and shows error about unexpected "compatible" property. The binding itself does not contain any properties but references syscon-common where iiuc compatible property must have at least 2 items and requires the "syscon" fallback.
>
> Mtk suggests splitting topmisc into the 2 blocks by only using the mux part as syscon with splitting the reg. If powerdomain really is needed then a second topmisc node could be added and bound to a new driver.

I agree with MediaTek's suggestion. Split it, that just makes more sense.

Besides, if the first part (the power controller in topmisc) is managed by ATF it's
a good idea to avoid touching anything in there from the kernel :-)


> But this would need a bit more of testing.
> regards Frank