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Date:   Mon, 04 Sep 2023 09:54:53 +0100
Message-ID: <86pm2ye2si.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Binbin Zhou <zhoubb.aaron@gmail.com>,
        Binbin Zhou <zhoubinbin@loongson.cn>,
        Huacai Chen <chenhuacai@loongson.cn>,
        Thomas Gleixner <tglx@linutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        loongson-kernel@lists.loongnix.cn, devicetree@vger.kernel.org,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org, diasyzhang@tencent.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] dt-bindings: interrupt-controller: loongson,liointc: Fix warnings about liointc-2.0
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On Wed, 30 Aug 2023 16:25:48 +0100,
Jiaxun Yang <jiaxun.yang@flygoat.com> wrote:
>=20
>=20
>=20
> =E5=9C=A8 2023/8/30 21:44, Marc Zyngier =E5=86=99=E9=81=93:
> [...]
> >> What's the best way, in your opinion, to overhaul this property? As we=
 don't
> >> really care backward compatibility of DTBs on those systems we can
> >> just redesign it.
> > You may not care about backward compatibility, but I do. We don't
> > break existing systems, full stop.
> Ah it won't break any existing system. Sorry for not giving enough insight
> into the platform in previous reply. As for Loongson64 all DTBs are built
> into kernel binary. So as long as binding are changed together with all D=
TS
> in tree we won't break any system.

This is factually wrong. QEMU produces a DT for Loongarch at runtime.
So no, you're not allowed to just drop bindings on the floor. They
stay forever.

> > As for the offending property, it has no place here either. DT is not
> > the place where you put "performance knobs".
> Hmm, I can see various bindings with vendor prefix exposing device
> configurations. If we seen this interrupt routing as a device configurati=
on
> I don't think it's against devicetree design philosophy.

Just because we have tons of crap in the device trees doesn't give you
a license to be just as bad.

	M.

--=20
Without deviation from the norm, progress is not possible.