Re: [PATCH 18/18] arm64: apple: Add initial Mac Mini 2020 (M1) devicetree

From: Rob Herring <robh@kernel.org>
To: Hector Martin <marcan@marcan.st>
Cc: Arnd Bergmann <arnd@kernel.org>,
	DTML <devicetree@vger.kernel.org>, Marc Zyngier <maz@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>, SoC Team <soc@kernel.org>,
	Olof Johansson <olof@lixom.net>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 18/18] arm64: apple: Add initial Mac Mini 2020 (M1) devicetree
Date: Mon, 8 Feb 2021 11:58:47 -0600	[thread overview]
Message-ID: <20210208175847.GB1567700@robh.at.kernel.org> (raw)
In-Reply-To: <f98dc238-6742-455e-3f76-e86ae4c0c838@marcan.st>

On Mon, Feb 08, 2021 at 11:12:52PM +0900, Hector Martin wrote:
> On 08/02/2021 21.40, Arnd Bergmann wrote:
> > On Mon, Feb 8, 2021 at 1:13 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> > > 
> > > On Mon, Feb 08, 2021 at 08:56:53PM +0900, Hector Martin 'marcan' wrote:
> > > > On 08/02/2021 20.04, Krzysztof Kozlowski wrote:
> > > > > apple
> > > > > 
> > > > > Don't make things different for this one platform (comparing to all
> > > > > other platforms). Apple is not that special. :)
> > > > 
> > > > AAPL is the old vendor prefix used in the PowerPC era. I'm happy to use
> > > > `apple`, as long as we're OK with having two different prefixes for the same
> > > > vendor, one for PPC and one for ARM64. I've seen opinions go both ways on
> > > > this one :)
> > > 
> > > Thanks for explanation. I propose to choose just "apple". Sticking to
> > > old vendor name is not a requirement - we have few vendor prefixes which
> > > were marked as deprecated because we switched to a better one.
> > 
> > We've gone back and forth on this a few times already. My current
> > preference would also be to go with "apple", not because it's somehow
> > nicer or clearer but because it avoids the namespace conflict with
> > what the Apple firmware uses:

It's only AAPL,phandle and AAPL,unit-string (equivalent to unit-address) 
AFAICT which are really internal format details. So it's really 'apple' 
that could conflct, but I can't see that mattering.

> Ack, I'll use 'apple' for v2.

3 votes for 'apple'. You all get to pick the color of this shed.

> Amusingly, Apple actually use 'apple,firestorm' and 'apple,icestorm' for the
> CPUs in their devicetrees for these machines, so those will end up identical
> :) (they don't use apple-related prefixes for any other compatible strings
> at all, it's a mess). But we don't care about what their ADTs (Apple DTs) do
> in Linux anyway, the bootloader abstracts all that out and we'll be dealing
> with mantaining proper DTs ourselves.
> 
> > > Makes sense. In such case it's indeed your work. Since you introduce it,
> > > the DTSes are usually licensed with (GPL-2.0+ OR MIT).
> > 
> > Indeed, we do want other OSs to use our dts files, so the general
> > preference is to have a permissive license, unless you have a strong
> > reason yourself to require GPL-only.
> 
> Thanks for pointing this out; this was actually unintentional. I based it
> off of an old dts I'd written ages ago and forgot to revisit the license. I
> even have it marked GPL-2.0+ in the copy in our bootloader repo, which is
> otherwise supposed to be MIT for original code...

I'll also highlight there's a DT only tree[1] available to import DT 
related parts to other projects. It's generated from the kernel tree. 
Probably an overkill to copying at this point though.

Rob

[1] https://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git/

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