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

[Andy Chiu]

On Sat, May 4, 2024 at 3:33 AM Charlie Jenkins <charlie@xxxxxxxxxxxx> wrote:
>
> From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxx>
> Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>

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

> ---
>  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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