From: Biju Das <biju.das.jz@bp.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 and disallow it for R-Car Gen3.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 v1->v2:
  * Added conditional check to disallow fd-only mode for R-Car Gen3.
---
 .../bindings/net/can/renesas,rcar-canfd.yaml  | 24 ++++++++++++++++---
 1 file changed, 21 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..a52244f0b5d1 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.
 
   assigned-clocks:
     description:
@@ -267,6 +275,16 @@ allOf:
       patternProperties:
         "^channel[6-7]$": false
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - renesas,rcar-gen3-canfd
+    then:
+      properties:
+        renesas,fd-only: false
+
 unevaluatedProperties: false
 
 examples:
-- 
2.43.0

On 23/11/2025 12:23, Biju wrote:
> From: Biju Das <biju.das.jz@bp.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 and disallow it for R-Car Gen3.
> 
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
>  v1->v2:
>   * Added conditional check to disallow fd-only mode for R-Car Gen3.
> ---
>  .../bindings/net/can/renesas,rcar-canfd.yaml  | 24 ++++++++++++++++---
>  1 file changed, 21 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..a52244f0b5d1 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:
> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:
> +      The CANFD on RZ/{G2L,G3E} and R-Car Gen4 SoCs support 3 modes FD-Only
> +      mode, Classical CAN mode and CAN-FD mode (default). In FD-Only mode,
> +      communication in Classical CAN frame format is disabled. Specify this
> +      property to put the controller in FD-Only mode.
>  
>    assigned-clocks:
>      description:
> @@ -267,6 +275,16 @@ allOf:
>        patternProperties:
>          "^channel[6-7]$": false
>  
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - renesas,rcar-gen3-canfd
> +    then:
> +      properties:
> +        renesas,fd-only: false
> +

You did not respond to my first paragraph from previous version. As I
said, you now need oneOf to restrict these, since you are not using
simple enum.

Best regards,
Krzysztof