Re: [PATCH v3 1/2] dt-bindings: media: renesas,vin: Add binding for V4M

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

Hi Conor,

On 2024-06-19 18:33:37 +0100, Conor Dooley wrote:
> On Wed, Jun 19, 2024 at 05:35:58PM +0200, Niklas Söderlund wrote:
> > Document support for the VIN module in the Renesas V4M (r8a779h0) SoC.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> 
> Didn't we just have a conversation about this, yet nothing has changed?
> NAK. Either you need a fallback or to explain why a fallback is not
> suitable _in this patch_.

Sorry, I'm confused from the conclusion of our conversation in v2. I did 
add an explanation to why not fallback is used, but I added it to patch 
2/2 which adds the compatible to the driver.

It was my understanding that a SoC specific compatible was needed in 
either case so, at lest to me, made more sens to explain why in the 
driver patch the reason go into detail about the register differences 
between the two. Sorry if I misunderstood. I can add the same 
explanation to both patches, would this help explain why only a SoC 
specific value is added?

  The datasheet for the two 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, 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, but to make this easy to address in the future do not add a
  common Gen4 fallback compatible. Instead uses SoC specific compatibles
  for both SoCs. This is what was done for Gen3 SoCs, which also had
  similar nuances in the register documentation.

> 
> Thanks,
> Conor.
> 
> > ---
> >  Documentation/devicetree/bindings/media/renesas,vin.yaml | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/media/renesas,vin.yaml b/Documentation/devicetree/bindings/media/renesas,vin.yaml
> > index 5539d0f8e74d..168cb02f8abe 100644
> > --- a/Documentation/devicetree/bindings/media/renesas,vin.yaml
> > +++ b/Documentation/devicetree/bindings/media/renesas,vin.yaml
> > @@ -54,6 +54,7 @@ properties:
> >                - renesas,vin-r8a77995 # R-Car D3
> >                - renesas,vin-r8a779a0 # R-Car V3U
> >                - renesas,vin-r8a779g0 # R-Car V4H
> > +              - renesas,vin-r8a779h0 # R-Car V4M
> >  
> >    reg:
> >      maxItems: 1
> > -- 
> > 2.45.2
> > 



-- 
Kind Regards,
Niklas Söderlund