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From:   Atish Patra <atishp@atishpatra.org>
Date:   Fri, 24 Dec 2021 21:52:31 -0800
Message-ID: <CAOnJCULK54pE1VX=Nt_cLLwSO5ytu_4w_+cnu5+NVnWemdzGeQ@mail.gmail.com>
Subject: Re: [PATCH v1 2/2] dt-bindings: riscv: Add DT binding for RISC-V ISA extensions
To:     Jessica Clarke <jrtc27@jrtc27.com>
Cc:     "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        Atish Patra <atishp@rivosinc.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Anup Patel <anup@brainfault.org>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        devicetree <devicetree@vger.kernel.org>,
        Jisheng Zhang <jszhang@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Rob Herring <robh+dt@kernel.org>
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On Fri, Dec 24, 2021 at 3:25 PM Jessica Clarke <jrtc27@jrtc27.com> wrote:
>
> On 24 Dec 2021, at 21:16, Atish Patra <atishp@atishpatra.org> wrote:
> >
> > RISC-V ISA extensions can be single letter or multi-letter names.
> > The single letter extensions are mostly base extensions and encoded in
> > "riscv,isa" DT property. However, parsing the multi-letter extensions
> > via the isa string is cumbersome and is not scalable.
> >
> > Add a new DT node for multi-letter extensions.
> >
> > Signed-off-by: Atish Patra <atishp@rivosinc.com>
> > ---
> > Documentation/devicetree/bindings/riscv/cpus.yaml | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Docume=
ntation/devicetree/bindings/riscv/cpus.yaml
> > index aa5fb64d57eb..6c4eecf389a9 100644
> > --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> > +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> > @@ -78,6 +78,15 @@ properties:
> >       - rv64imac
> >       - rv64imafdc
> >
> > +  riscv,isa-ext:
> > +    description:
> > +      Identifies the specific RISC-V instruction set architecture exte=
nsions
> > +      supported by one or multiple harts. All the multi-letter extensi=
ons
> > +      should be listed here as a boolean property. This subnode can be=
 under
> > +      /cpus or under individual cpu node. In case of former, it repres=
ent
> > +      the common ISA extensions for all harts. The name of the boolean=
 property
> > +      must match the actual ISA extension name in all lowercase format=
.
>
> I don=E2=80=99t see why this needs explicitly calling out, that=E2=80=99s=
 true in
> general of cpu node properties (3.8p4 of the Devicetree spec v0.4-rc1 /
> v0.3-40-g7e1cc17), not that I like it.
>

Thanks for pointing it out. I did not realize the DT specification
already has a paragraph
about this. I will update the description in the next version.

> Jess
>


--=20
Regards,
Atish