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From:   Anup Patel <anup@brainfault.org>
Date:   Mon, 25 Oct 2021 09:47:34 +0530
Message-ID: <CAAhSdy1N-UQFnbFc7PSwf62y=gbvX7pK=vwUaG8m_KzdWx3AgQ@mail.gmail.com>
Subject: Re: [RESEND PATCH V3 1/2] dt-bindings: riscv: add mmu-supports-svpbmt
 for Svpbmt
To:     Wei Fu <wefu@redhat.com>
Cc:     Anup Patel <anup.patel@wdc.com>, Atish Patra <atish.patra@wdc.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        Guo Ren <guoren@kernel.org>,
        =?UTF-8?Q?Christoph_M=C3=BCllner?= <christoph.muellner@vrull.eu>,
        Philipp Tomsich <philipp.tomsich@vrull.eu>,
        Christoph Hellwig <hch@lst.de>,
        liush <liush@allwinnertech.com>,
        =?UTF-8?B?V2VpIFd1ICjlkLTkvJ8p?= <lazyparser@gmail.com>,
        Drew Fustini <drew@beagleboard.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        taiten.peng@canonical.com,
        Aniket Ponkshe <aniket.ponkshe@canonical.com>,
        Heinrich Schuchardt <heinrich.schuchardt@canonical.com>,
        Gordan Markus <gordan.markus@canonical.com>,
        Guo Ren <guoren@linux.alibaba.com>,
        Arnd Bergmann <arnd@arndb.de>, Chen-Yu Tsai <wens@csie.org>,
        Maxime Ripard <maxime@cerno.tech>,
        Daniel Lustig <dlustig@nvidia.com>,
        Greg Favor <gfavor@ventanamicro.com>,
        Andrea Mondelli <andrea.mondelli@huawei.com>,
        Jonathan Behrens <behrensj@mit.edu>,
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        Palmer Dabbelt <palmer@dabbelt.com>,
        Rob Herring <robh+dt@kernel.org>
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On Mon, Oct 25, 2021 at 9:36 AM <wefu@redhat.com> wrote:
>
> From: Wei Fu <wefu@redhat.com>
>
> Previous patch has added svpbmt in arch/riscv and changed the
> DT mmu-type. Update dt-bindings related property here.
>
> Signed-off-by: Wei Fu <wefu@redhat.com>
> Co-developed-by: Guo Ren <guoren@kernel.org>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> Cc: Anup Patel <anup@brainfault.org>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> ---
>  Documentation/devicetree/bindings/riscv/cpus.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> index e534f6a7cfa1..76f324d85e12 100644
> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -59,6 +59,11 @@ properties:
>        - riscv,sv48
>        - riscv,none
>
> +  mmu-supports-svpbmt:
> +    description:
> +      Describes the CPU's mmu-supports-svpbmt support
> +    $ref: '/schemas/types.yaml#/definitions/phandle'

There were various proposals from different folks in the previous
email threads.

I think most of us were converging on:
1) Don't modify "mmu-type" DT property for backward
compatibility
2) Add boolean DT property "riscv,svpmbt" under
"mmu" child DT node of each CPU DT node. Same will apply
to boolean DT property "riscv,svnapot" as well.

We also have bitmanip and vector broken down into smaller
extensions so grouping related extensions as separate DT node
under each CPU node will be more readable and easy to parse.

Regards,
Anup

> +
>    riscv,isa:
>      description:
>        Identifies the specific RISC-V instruction set architecture
> --
> 2.25.4
>