linux-kernel - Re: [PATCH v6 02/17] dt-bindings: riscv: cpus: add a vlen register length property

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Message-ID: <CABgGipXNoiQ-+R3CzFS_hGT+d9L9vhqyB1famkDmm=v8XcYavg@mail.gmail.com>
Date: Thu, 16 May 2024 20:50:45 +0800
From: Andy Chiu <andy.chiu@...ive.com>
To: Charlie Jenkins <charlie@...osinc.com>
Cc: Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, 
	Conor Dooley <conor.dooley@...rochip.com>, Evan Green <evan@...osinc.com>, 
	Clément Léger <cleger@...osinc.com>, 
	Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>, linux-riscv@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Palmer Dabbelt <palmer@...osinc.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-sunxi@...ts.linux.dev, linux-doc@...r.kernel.org, 
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v6 02/17] dt-bindings: riscv: cpus: add a vlen register
 length property

On Sat, May 4, 2024 at 3:33 AM Charlie Jenkins <charlie@...osinc.com> wrote:
>
> From: Conor Dooley <conor.dooley@...rochip.com>
>
> Add a property analogous to the vlenb CSR so that software can detect
> the vector length of each CPU prior to it being brought online.
> Currently software has to assume that the vector length read from the
> boot CPU applies to all possible CPUs. On T-Head CPUs implementing
> pre-ratification vector, reading the th.vlenb CSR may produce an illegal
> instruction trap, so this property is required on such systems.
>
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>

Reviewed-by: Andy Chiu <andy.chiu@...ive.com>

> ---
>  Documentation/devicetree/bindings/riscv/cpus.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> index d87dd50f1a4b..edcb6a7d9319 100644
> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -94,6 +94,12 @@ properties:
>      description:
>        The blocksize in bytes for the Zicboz cache operations.
>
> +  riscv,vlenb:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description:
> +      VLEN/8, the vector register length in bytes. This property is required in
> +      systems where the vector register length is not identical on all harts.
> +
>    # RISC-V has multiple properties for cache op block sizes as the sizes
>    # differ between individual CBO extensions
>    cache-op-block-size: false
>
> --
> 2.44.0
>
>
> _______________________________________________
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> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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