Re: [PATCH v3 2/8] dt-bindings: can: renesas,rcar-canfd: Document RZ/G3S SoC

[Rob Herring (Arm)]

On Tue, 14 Jul 2026 20:33:09 +0300, Claudiu Beznea wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> 
> The CAN FD controller found on the Renesas RZ/G3S SoC is largely compatible
> with the variant present on the RZ/G3E SoC. The main differences are:
> - the RZ/G3S provides only two CAN FD channels
> - the RZ/G3S supports only CAN FD operation; the Channel n CAN FD
>   Configuration Register does not implement the bits used to select
>   classical CAN-only mode (bit 30) or CAN FD-only mode (bit 28);
>   consequently, bit 31 (CAN FD Frame Distinction Enable) of the same
>   register is also not implemented
> - some bits in several registers (mainly reserved or status bits) are
>   read-write on the RZ/G3S but read-only on the RZ/G3E; their behavior is
>   otherwise identical: the bits read back as 0 on both SoCs and software
>   is allowed to write only 0 to them on the RZ/G3S
> - the RZ/G3S provides 256 acceptance filters, compared to 768 on the
>   RZ/G3E
> - the RZ/G3S can use PCLK clock as the CAN FD clock source through an
>   internal clock divider, while also supporting an external CAN FD clock
>   source
> 
> Since:
> - the SoC clock generator provides to the CAN IP only the peripheral and
>   the RAM clocks
> - when sourced from the peripheral clock, the CAN-FD clock is obtained
>   inside the IP itself by dividing the peripheral clock
> - the assigned-clocks and assigned-clock-rates properties are specific to
>   the CAN-FD clock
> the assigned-clocks and assigned-clock-rates properties were dropped from
> the required properties list of the Renesas RZ/G3S SoC.
> 
> Add documentation for the Renesas RZ/G3S SoC.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> ---
> 
> Changes in v3:
> - updated the patch description to reflect RZ/G3S has 256 acceptance
>   filters and RZ/G3E has 768 acceptance filters
> - kept compatibles alphanumerically sorted
> 
> Changes in v2:
> - forbid renesas,no-can-fd and renesas,fd-only since the IP supports
>   only CAN-FD; for this didn't collect Biju's tag
> 
>  .../bindings/net/can/renesas,rcar-canfd.yaml  | 20 +++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 

Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx>