Subject: Re: [PATCH v2 3/8] irqchip/apple-aic: Add cpumasks for E and P cores
To:     Marc Zyngier <maz@kernel.org>, Mark Rutland <mark.rutland@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Will Deacon <will@kernel.org>,
        Sven Peter <sven@svenpeter.dev>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        Rob Herring <robh+dt@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dougall <dougallj@gmail.com>, kernel-team@android.com
References: <20211201134909.390490-1-maz@kernel.org>
 <20211201134909.390490-4-maz@kernel.org> <Yaed7VAlwwCBcP13@FVFF77S0Q05N>
 <87zgphlkdx.wl-maz@kernel.org>
From:   Hector Martin <marcan@marcan.st>
Message-ID: <d350f759-17de-907f-531b-127d2493d056@marcan.st>
Date:   Sun, 12 Dec 2021 16:22:00 +0900
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On 04/12/2021 01.32, Marc Zyngier wrote:
> On Wed, 01 Dec 2021 16:08:13 +0000,
> Mark Rutland <mark.rutland@arm.com> wrote:
>>
>> On Wed, Dec 01, 2021 at 01:49:04PM +0000, Marc Zyngier wrote:
>>> In order to be able to tell the core IRQ code about the affinity
>>> of the PMU interrupt in later patches, compute the cpumasks of the
>>> P and E cores at boot time.
>>>
>>> This relies on the affinity scheme used by the vendor, which seems
>>> to work for the couple of SoCs that are out in the wild.
>>
>> ... but may change at any arbitrary point in future?
> 
> Crystal balls are in short supply, sorry! ;-)

Considering Apple seem to rely on this all over the place, I think they 
probably won't be changing the meaning of Aff2 at least until they 
decide to come up with SoCs that have 3 types of cores, or something 
like that :)

But yeah, ultimately this is a guess.

-- 
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub