Re: [PATCH v5 1/6] dt-bindings: media: renesas,vin: Add Gen4 family fallback

[Krzysztof Kozlowski <krzk@kernel.org>]

On 04/07/2024 18:16, Niklas Söderlund wrote:
> The Gen4 SoCs V3U, V4H and V4M have a similar video capture pipelines.
> 
> The datasheets for the SoCs have small nuances around the Pre-Clip
> registers ELPrC and EPPrC in three use-cases, interlaced images,
> embedded data and RAW8 input. On V4H the values written to the registers
> are based on odd numbers while on V4M they are even numbers, values are
> based on the input image size. No board that uses these SoCs which also
> have the external peripherals to test these nuances exists. Most likely
> this is an issue in the datasheet.
> 
> Before adding bindings for V4M add a family compatible fallback for
> Gen4. That way the driver only needs to be updated once for Gen4, and we
> still have the option to fix any problems in the driver if any testable
> differences between the SoCs are found.
> 
> There are already DTS files using the V3U and V4H compatibles which
> needs to be updated to not produce a warning for DTS checks. The driver
> also needs to kept the compatible values to be backward compatible , but
> for new Gen4 SoCs such as V4M we can avoid this.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> * Changes since v4
> - Added V3U to the list of Gen4 devices.
> 
> * Changes since v3
> - New in v4.
> ---
>  Documentation/devicetree/bindings/media/renesas,vin.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/media/renesas,vin.yaml b/Documentation/devicetree/bindings/media/renesas,vin.yaml
> index 5539d0f8e74d..aa16f1528f2d 100644
> --- a/Documentation/devicetree/bindings/media/renesas,vin.yaml
> +++ b/Documentation/devicetree/bindings/media/renesas,vin.yaml
> @@ -52,8 +52,11 @@ properties:
>                - renesas,vin-r8a77980 # R-Car V3H
>                - renesas,vin-r8a77990 # R-Car E3
>                - renesas,vin-r8a77995 # R-Car D3
> +      - items:
> +          - enum:
>                - renesas,vin-r8a779a0 # R-Car V3U
>                - renesas,vin-r8a779g0 # R-Car V4H
> +          - const: renesas,rcar-gen4-vin # Generic R-Car Gen4

I believe it was requested in earlier comments to use SoC specific
compatible as fallback.

See:
https://lore.kernel.org/all/20240624-rented-danger-300652ab8eeb@wendy/
https://lore.kernel.org/all/20240610-screen-wolverine-78370c66d40f@spud/
https://lore.kernel.org/all/20240620-gating-coherent-af984389b2d7@spud/

You ignored these suggestions and decided to go with other approach.

I don't agree with this.

Please carry:

Nacked-by: Krzysztof Kozlowski <krzk@kernel.org>

so my objection and your avoidance of earlier suggestions will be
clearly documented.

Best regards,
Krzysztof