Re: [PATCH v10 02/14] dt-bindings: cpus: add a thead vlen register length property

[Andy Chiu]

Charlie Jenkins <charlie@xxxxxxxxxxxx> 於 2024年9月12日 週四 下午1:57寫道：
>
> 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: Charlie Jenkins <charlie@xxxxxxxxxxxx>
> Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

Reviewed-by: Andy Chiu <andybnac@xxxxxxxxx>

> ---
>  Documentation/devicetree/bindings/riscv/cpus.yaml | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> index 8edc8261241a..c0cf6cf56749 100644
> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -26,6 +26,18 @@ description: |
>  allOf:
>    - $ref: /schemas/cpu.yaml#
>    - $ref: extensions.yaml
> +  - if:
> +      not:
> +        properties:
> +          compatible:
> +            contains:
> +              enum:
> +                - thead,c906
> +                - thead,c910
> +                - thead,c920
> +    then:
> +      properties:
> +        thead,vlenb: false
>
>  properties:
>    compatible:
> @@ -95,6 +107,13 @@ properties:
>      description:
>        The blocksize in bytes for the Zicboz cache operations.
>
> +  thead,vlenb:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description:
> +      VLEN/8, the vector register length in bytes. This property is required on
> +      thead systems where the vector register length is not identical on all harts, or
> +      the vlenb CSR is not available.
> +
>    # RISC-V has multiple properties for cache op block sizes as the sizes
>    # differ between individual CBO extensions
>    cache-op-block-size: false
>
> --
> 2.45.0
>
>
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