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Date:   Sun, 4 Jun 2023 22:08:02 +0100
From:   Conor Dooley <conor@kernel.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Varshini Rajendran <varshini.rajendran@microchip.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        krzysztof.kozlowski+dt@linaro.org,
        Conor Dooley <conor+dt@kernel.org>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Stephen Boyd <sboyd@kernel.org>,
        Sebastian Reichel <sre@kernel.org>,
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Subject: Re: [PATCH 15/21] dt-bindings: irqchip/atmel-aic5: Add support for
 sam9x7 aic
Message-ID: <20230604-cohesive-unmoving-032da3272620@spud>
References: <20230603200243.243878-1-varshini.rajendran@microchip.com>
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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,
> >>=20
> >> 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
> >>=20
> >> 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?
>=20
> 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.
>=20
> 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.
>=20
> 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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