Re: [PATCH v5 2/6] dt-bindings: dma: rz-dmac: Document RZ/V2H(P) family of SoCs

[Geert Uytterhoeven]

Hi Fabrizio,

On Wed, 5 Mar 2025 at 01:21, Fabrizio Castro
<fabrizio.castro.jz@xxxxxxxxxxx> wrote:
> Document the Renesas RZ/V2H(P) family of SoCs DMAC block.
> The Renesas RZ/V2H(P) DMAC is very similar to the one found on the
> Renesas RZ/G2L family of SoCs, but there are some differences:
> * It only uses one register area
> * It only uses one clock
> * It only uses one reset
> * Instead of using MID/IRD it uses REQ No
> * It is connected to the Interrupt Control Unit (ICU)
>
> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
> v4->v5:
> * Removed ACK No from the specification of the dma cell.
> * I have kept the tags received as this is a minor change and the
>   structure remains the same as v4. Please let me know if this is
>   not okay.

Thanks for the update!

> --- a/Documentation/devicetree/bindings/dma/renesas,rz-dmac.yaml
> +++ b/Documentation/devicetree/bindings/dma/renesas,rz-dmac.yaml
> @@ -61,14 +66,21 @@ properties:
>    '#dma-cells':
>      const: 1
>      description:
> -      The cell specifies the encoded MID/RID values of the DMAC port

Please just insert "or the REQ No" and be done with it?

> -      connected to the DMA client and the slave channel configuration
> -      parameters.
> +      For the RZ/A1H, RZ/Five, RZ/G2{L,LC,UL}, RZ/V2L, and RZ/G3S SoCs, the cell
> +      specifies the encoded MID/RID values of the DMAC port connected to the
> +      DMA client and the slave channel configuration parameters.
>        bits[0:9] - Specifies MID/RID value
>        bit[10] - Specifies DMA request high enable (HIEN)
>        bit[11] - Specifies DMA request detection type (LVL)
>        bits[12:14] - Specifies DMAACK output mode (AM)
>        bit[15] - Specifies Transfer Mode (TM)
> +      For the RZ/V2H(P) SoC the cell specifies the DMAC REQ No and the slave channel
> +      configuration parameters.
> +      bits[0:9] - Specifies the DMAC REQ No
> +      bit[10] - Specifies DMA request high enable (HIEN)
> +      bit[11] - Specifies DMA request detection type (LVL)
> +      bits[12:14] - Specifies DMAACK output mode (AM)
> +      bit[15] - Specifies Transfer Mode (TM)

... so the casual reader doesn't have to look for the (nonexisting)
differences in the other bits.

>
>    dma-channels:
>      const: 16
> @@ -80,12 +92,29 @@ properties:
>      items:
>        - description: Reset for DMA ARESETN reset terminal
>        - description: Reset for DMA RST_ASYNC reset terminal
> +    minItems: 1
>
>    reset-names:
>      items:
>        - const: arst
>        - const: rst_async
>
> +  renesas,icu:
> +    description:
> +      On the RZ/V2H(P) SoC configures the ICU to which the DMAC is connected to.

Are other SoCs with ICU planned?

> +      It must contain the phandle to the ICU, and the index of the DMAC as seen
> +      from the ICU (e.g. parameter k from register ICU_DMkSELy).

This is already described more formally below

> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    items:
> +      - items:
> +          - description: phandle to the ICU node.
> +          - description: The DMAC index.
> +              4 for DMAC0
> +              0 for DMAC1
> +              1 for DMAC2
> +              2 for DMAC3
> +              3 for DMAC4

Other SoCs may have other mappings.
So perhaps leave out the translation table, but write:

    The number of the DMAC as seen from the ICU, i.e. parameter k from
register ICU_DMkSELy.
    This may differ from the actual DMAC instance number!

> +
>  required:
>    - compatible
>    - reg
> @@ -98,13 +127,25 @@ allOf:
>    - $ref: dma-controller.yaml#
>
>    - if:
> -      not:
> -        properties:
> -          compatible:
> -            contains:
> -              enum:
> -                - renesas,r7s72100-dmac
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - renesas,r9a07g043-dmac
> +              - renesas,r9a07g044-dmac
> +              - renesas,r9a07g054-dmac
> +              - renesas,r9a08g045-dmac
>      then:
> +      properties:
> +        reg:
> +          minItems: 2
> +        clocks:
> +          minItems: 2
> +        resets:
> +          minItems: 2
> +
> +        renesas,icu: false
> +
>        required:
>          - clocks
>          - clock-names
> @@ -112,13 +153,42 @@ allOf:
>          - resets
>          - reset-names
>
> -    else:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: renesas,r7s72100-dmac
> +    then:
>        properties:

    reg:
        minItems: 2

>          clocks: false
>          clock-names: false
>          power-domains: false
>          resets: false
>          reset-names: false
> +        renesas,icu: false
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: renesas,r9a09g057-dmac
> +    then:
> +      properties:
> +        reg:
> +          maxItems: 1
> +        clocks:
> +          maxItems: 1
> +        resets:
> +          maxItems: 1
> +
> +        clock-names: false
> +        reset-names: false
> +
> +      required:
> +        - clocks
> +        - power-domains
> +        - renesas,icu
> +        - resets
>
>  additionalProperties: false

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds