Re: [PATCH v3 2/4] dt-bindings: mips: brcm: Document brcm,bmips-cbr-reg property

From: Conor Dooley
Date: Wed May 08 2024 - 13:15:14 EST


On Wed, May 08, 2024 at 07:07:18PM +0200, Christian Marangi wrote:
> Document brcm,bmips-cbr-reg property.
>
> Some SoC suffer from a BUG where read_c0_brcm_cbr() might return 0
> if called from TP1. The CBR address is always the same on the SoC
> hence it can be provided in DT to handle broken case where bootloader
> doesn't init it or SMP where read_c0_brcm_cbr() returns 0 from TP1.
>
> Usage of this property is to give an address also in these broken
> configuration/bootloader.
>
> Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
> ---
> .../devicetree/bindings/mips/brcm/soc.yaml | 23 +++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mips/brcm/soc.yaml b/Documentation/devicetree/bindings/mips/brcm/soc.yaml
> index 975945ca2888..77f73ab48c11 100644
> --- a/Documentation/devicetree/bindings/mips/brcm/soc.yaml
> +++ b/Documentation/devicetree/bindings/mips/brcm/soc.yaml
> @@ -55,6 +55,15 @@ properties:
> under the "cpus" node.
> $ref: /schemas/types.yaml#/definitions/uint32
>
> + brcm,bmips-cbr-reg:
> + description: Reference address of the CBR.

Pretty sure that Rob commented last time that there's no definition
anywhere here of CBR, but I don't see either a response to him or an
explanation in v3 as to what CBR means.

> + Some SoC suffer from a BUG where read_c0_brcm_cbr() might
> + return 0 if called from TP1. The CBR address is always the
> + same on the SoC hence it can be provided in DT to handle
> + broken case where bootloader doesn't initialise it or SMP
> + where read_c0_brcm_cbr() returns 0 from TP1.

Why is a ?linux? function name in the binding? Surely this is just
"or in SMP systems where reading CBR returns 0 from...", no? Ditto
above.

Thanks,
Conor.

> + $ref: /schemas/types.yaml#/definitions/uint32
> +
> patternProperties:
> "^cpu@[0-9]$":
> type: object
> @@ -64,6 +73,20 @@ properties:
> required:
> - mips-hpt-frequency
>
> +if:
> + properties:
> + compatible:
> + contains:
> + enum:
> + - brcm,bcm6358
> + - brcm,bcm6368
> +
> +then:
> + properties:
> + cpus:
> + required:
> + - brcm,bmips-cbr-reg
> +
> additionalProperties: true
>
> examples:
> --
> 2.43.0
>

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