Re: [PATCH v1 12/30] dt-bindings: reset: Add starfive,jh7110-reset bindings

Hal Feng
2022-10-12T15:21:59Z

On Wed, 12 Oct 2022 15:05:04 +0100, Conor Dooley wrote:
> Hey Hal Feng,
>
> On Wed, Oct 12, 2022 at 09:33:42AM -0400, Krzysztof Kozlowski wrote:
> > >>> These two properties are the key differences among different reset controllers.
> > >>
> > >> Different as in different compatibles? Please answer the questions..>
> > >>> There are five memory regions for clock and reset in StarFive JH7110 SoC. They
> > >>> are "syscrg", "aoncrg", "stgcrg", "ispcrg" and "voutcrg". Each memory region
> > >>> has different reset ASSERT/STATUS register offset and different number of reset
> > >>> signals.
> > >>
> > >> Then these are not exactly the same devices, so using one compatible for
> > >> them does not look correct.
> > >
> > > One compatible can just be matched by one device? I think this is what
> > > confuses me.
> >
> > I don't understand the question.
>
> If two SoCs have exactly the same device/peripheral then they _can_ use
> the same compatible. If they share some common, viable feature-set then
> one can "fall back" to the other depending on what your Venn diagram of
> common features looks like. I've not been following this too closely,
> but I think what Krzysztof is suggesting is that you have a jh7100 and
> a jh7110 compatible. Then in your driver you just "know" that if you
> match against jh7110 which values to use for register offsets & vice
> versa for a match against the jh7100. There's many examples over the
> tree for how to handle this sort of thing rather than including it in
> the devicetree.
>
> Maybe Rob and Krzysztof will scream at me for this description, but
> devicetree is about how periperhals etc are connected together in the
> system not about the internals of a given peripheral.
>
> Following that logic, the devicetree should not contain register offsets
> etc that are a known quanitity once you've determined that you are running
> on vendor,soc-foo.
>
> Hopefully that helps with your confusion somewhat?
> Conor.

Yes, anyway, thank you for the detailed reply.

Best regards,
Hal