linux-kernel - Re: [PATCH 1/2] dt-bindings: can: renesas,rcar-canfd: Document renesas,fd-only property

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Message-ID: <20251120-statuesque-heavy-herring-e915f6@kuoka>
Date: Thu, 20 Nov 2025 09:09:06 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Biju <biju.das.au@...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>, 
	Biju Das <biju.das.jz@...renesas.com>, Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	linux-can@...r.kernel.org, devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH 1/2] dt-bindings: can: renesas,rcar-canfd: Document
 renesas,fd-only property

On Tue, Nov 18, 2025 at 02:18:34PM +0000, Biju wrote:
> From: Biju Das <biju.das.jz@...renesas.com>
> 
> The CANFD on RZ/{G2L,G3E} and R-Car Gen4 support 3 modes FD-Only mode,
> Classical CAN mode and CAN-FD mode. In FD-Only mode, communication in
> Classical CAN frame format is disabled. Document renesas,fd-only to handle
> this mode. As these SoCs support 3 modes, update the description of
> renesas,no-can-fd property.
> 
> Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
> ---
>  .../bindings/net/can/renesas,rcar-canfd.yaml       | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> index f4ac21c68427..bf9a7d5288d3 100644
> --- a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> +++ b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
> @@ -125,9 +125,17 @@ properties:
>    renesas,no-can-fd:
>      $ref: /schemas/types.yaml#/definitions/flag
>      description:
> -      The controller can operate in either CAN FD only mode (default) or
> -      Classical CAN only mode.  The mode is global to all channels.
> -      Specify this property to put the controller in Classical CAN only mode.
> +      The controller can operate in either CAN-FD mode (default) or FD-Only
> +      mode (RZ/{G2L,G3E} and R-Car Gen4) or Classical CAN mode. Specify this
> +      property to put the controller in Classical CAN mode.
> +
> +  renesas,fd-only:
> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:
> +      The CANFD on RZ/{G2L,G3E} and R-Car Gen4 SoCs support 3 modes FD-Only
> +      mode, Classical CAN mode and CAN-FD mode (default). In FD-Only mode,
> +      communication in Classical CAN frame format is disabled. Specify this
> +      property to put the controller in FD-Only mode.

It should really be just an enum since the beginning - representing the
mode of operation. Now you need to complex oneOf to disallow usage of
both.

You also claim not all devices support this, so you need to disallow it
per variant.

Best regards,
Krzysztof