linux-kernel - Re: [PATCH v3 3/4] dt-bindings: can: renesas,rcar-canfd: Document RZ/T2H and RZ/N2H SoCs

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Message-ID: <20260111-poetic-dark-butterfly-97993f@quoll>
Date: Sun, 11 Jan 2026 11:14:01 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>, 
	Vincent Mailhol <mailhol@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, linux-can@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Biju Das <biju.das.jz@...renesas.com>, Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v3 3/4] dt-bindings: can: renesas,rcar-canfd: Document
 RZ/T2H and RZ/N2H SoCs

On Fri, Jan 09, 2026 at 12:51:27PM +0000, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Document the CAN-FD controller used on the RZ/T2H and RZ/N2H SoCs. The
> CAN-FD IP is largely compatible with the R-Car Gen4 block, but differs
> in that AFLPN and CFTML are different, there is no reset line for the IP,
> and it only supports two channels.
> 
> The schema already enforces reset-names only for RZ/G2L and RZ/G3E and
> disallows it for all other SoCs, so only the resets property is explicitly
> marked as unsupported for RZ/T2H and RZ/N2H.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> v2->v3:
> - Grouped single compatible entries into an enum.
> - Updated commit message about disallowing reset-names property.
> - Added Reviewed-by tag.
> 
> v1->v2:
> - No changes made.
> ---
>  .../bindings/net/can/renesas,rcar-canfd.yaml  | 29 +++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> index fb709cfd26d7..ceb072e0a304 100644
> --- a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> +++ b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> @@ -42,7 +42,10 @@ properties:
>                - renesas,r9a07g054-canfd    # RZ/V2L
>            - const: renesas,rzg2l-canfd     # RZ/G2L family
>  
> -      - const: renesas,r9a09g047-canfd     # RZ/G3E
> +      - items:

The convention is enum and that's what I asked. I know it is a nit, but
if I give review now for this code which I disagreed, my disagreement
won't be ever recorded and people in future work will base on this less
preferred syntax.

So again:

- enum:
    - foo
    - bar

> +          - enum:
> +              - renesas,r9a09g047-canfd    # RZ/G3E
> +              - renesas,r9a09g077-canfd    # RZ/T2H
>  
>        - items:
>            - enum:
> @@ -50,6 +53,10 @@ properties:
>                - renesas,r9a09g057-canfd     # RZ/V2H(P)
>            - const: renesas,r9a09g047-canfd
>  
> +      - items:
> +          - const: renesas,r9a09g087-canfd  # RZ/N2H
> +          - const: renesas,r9a09g077-canfd
> +
>    reg:
>      maxItems: 1
>  
> @@ -179,7 +186,6 @@ required:
>    - clocks
>    - clock-names
>    - power-domains
> -  - resets
>    - assigned-clocks
>    - assigned-clock-rates
>    - channel0
> @@ -243,11 +249,30 @@ allOf:
>            minItems: 2
>            maxItems: 2
>  
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: renesas,r9a09g077-canfd
> +    then:
> +      properties:
> +        interrupts:
> +          maxItems: 8
> +
> +        interrupt-names:
> +          maxItems: 8
> +
> +        resets: false
> +    else:
> +      required:
> +        - resets

I do not think you are making this binding easy to maintain. You have
now multiple separate ifs AND two ifs with "else:" condition. Try to
understand which condition/description applies to "rcar-gen3". Does it
require resets? Let's look for the compatible in the file - you find
"if:" block requiring reset-names but no "require" for resets. Odd.

As I said last time, these should be alwaysy synced.

The binding was not in a good shape before but you are not improving it.

Best regards,
Krzysztof