Re: [PATCH 15/21] dt-bindings: irqchip/atmel-aic5: Add support for sam9x7 aic

[Conor Dooley <conor@kernel.org>]

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On Sun, Jun 04, 2023 at 11:49:48AM +0200, Arnd Bergmann wrote:
> On Sat, Jun 3, 2023, at 23:23, Conor Dooley wrote:
> > On Sat, Jun 03, 2023 at 10:19:50PM +0100, Conor Dooley wrote:
> >> Hey Varshini,
> >> 
> >> On Sun, Jun 04, 2023 at 01:32:37AM +0530, Varshini Rajendran wrote:
> >> > Document the support added for the Advanced interrupt controller(AIC)
> >> > chip in the sam9x7 soc family
> >> 
> >> Please do not add new family based compatibles, but rather use per-soc
> >> compatibles instead.
> >
> > These things leave me penally confused. Afaiu, sam9x60 is a particular

s/penally/perennially/

> > SoC. sam9x7 is actually a family, containing sam9x70, sam9x72 and
> > sam9x75. It would appear to me that each should have its own compatible,
> > no?
> 
> I think the usual way this works is that the sam9x7 refers to the
> SoC design as in what is actually part of the chip, whereas the 70,
> 72 and 75 models are variants that have a certain subset of the
> features enabled.
> 
> If that is the case here, then referring to the on-chip parts by
> the sam9x7 name makes sense, and this is similar to what we do
> on TI AM-series chips.

If it is the case that what differentiates them is having bits chopped
off, and there's no implementation differences that seems fair.

> There is a remaining risk that a there would be a future
> sam9x71/73/74/76/... product based on a new chip that uses
> incompatible devices, but at that point we can still use the
> more specific model number to identify those without being
> ambiguous. The same thing can of course happen when a SoC
> vendor reuses a specific name of a prior product with an update
> chip that has software visible changes.
> 
> I'd just leave this up to Varshini and the other at91 maintainers
> here, provided they understand the exact risks.

Ye, seems fair to me. Nicolas/Claudiu etc, is there a convention to use
the "0" model as the compatible (like the 9x60 did) or have "random"
things been done so far?

> It's different for the parts that are listed as just sam9x60
> compatible in the DT, I think those clearly need to have sam9x7
> in the compatible list, but could have the sam9x60 identifier
> as a fallback if the hardware is compatible.

Aye.

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