On 2024-06-24 11:36:40 +0100, Conor Dooley wrote: > On Mon, Jun 24, 2024 at 11:20:29AM +0200, Niklas Söderlund wrote: > > Hi Conor, > > > > On 2024-06-21 09:21:24 +0200, Geert Uytterhoeven wrote: > > > Hi Niklas, > > > > > > On Thu, Jun 20, 2024 at 7:22 PM Niklas Söderlund > > > <niklas.soderlund+renesas@xxxxxxxxxxxx> wrote: > > > > On 2024-06-20 17:27:00 +0100, Conor Dooley wrote: > > > > > > + - items: > > > > > > + - enum: > > > > > > - renesas,vin-r8a779g0 # R-Car V4H > > > > > > + - renesas,vin-r8a779h0 # R-Car V4M > > > > > > + - const: renesas,rcar-gen4-vin # Generic R-Car Gen4 > > > > > > > > > > > > If so I can see that working as I could still fix any issues that come > > > > > > from differences between V4H and V4M if needed. If so do you think it > > > > > > best to add this in two different patches? One to add the > > > > > > renesas,rcar-gen4-vin fallback (which will also need DTS updates to fix > > > > > > warnings from exciting users of V4H not listing the gen4 fallback) and > > > > > > one to add V4M? > > > > > > > > > > > > > > > I would just do: > > > > > diff --git a/Documentation/devicetree/bindings/media/renesas,vin.yaml b/Documentation/devicetree/bindings/media/renesas,vin.yaml > > > > > index 5539d0f8e74d..22bbad42fc03 100644 > > > > > --- a/Documentation/devicetree/bindings/media/renesas,vin.yaml > > > > > +++ b/Documentation/devicetree/bindings/media/renesas,vin.yaml > > > > > @@ -54,6 +54,9 @@ properties: > > > > > - renesas,vin-r8a77995 # R-Car D3 > > > > > - renesas,vin-r8a779a0 # R-Car V3U > > > > > - renesas,vin-r8a779g0 # R-Car V4H > > > > > + - items: > > > > > + - const: renesas,vin-r8a779h0 # R-Car V4L2 > > > > > + - const: renesas,vin-r8a779g0 # R-Car V4H > > > > > > > > @Geert: What do you think about this? This would be a first use-case for > > > > compatibles crossing SoC DTS files that I know of. I'm a bit uneasy > > > > going down this road. > > > > > > Me too ;-) > > > > > > > Would this not also effect the existing users of renesas,vin-r8a779g0 > > > > which would now need something similar to what you propose below with a > > > > list of SoC compatibles and a fallback. > > > > > > > > > > > > > > reg: > > > > > maxItems: 1 > > > > > > > > > > Which requires no driver or dts changes. That could become: > > > > > - items: > > > > > - enum: > > > > > - renesas,vin-r8a779h0 # R-Car V4L2 > > > > > - renesas,vin-r8a779i0 # R-Car R4P17 > > > > > - const: renesas,vin-r8a779g0 # R-Car V4H > > > > > > > > FWIW, on Gen2 where fallback es where useful compared to Gen3 we did > > > > this with "renesas,rcar-gen2-vin". > > > > > > We do know there are differences (albeit probably small) among the R-Car > > > Gen4 VIN implementations, so I am reluctant to add a family-specific > > > compatible value. Typically we only use a family-specific compatible > > > value if the IP cores are known (or better, assumed ;-) to be identical. > > > > > > And sometimes our assumptions turn out to be wrong... > > > See slides 25-33 (last two for the numbers) of my talk at ER2019 > > > https://embedded-recipes.org/2019/talks/herd-your-socs-become-a-matchmaker/ > > > > Do Geert's slides help to explain the R-Car perspective on why a > > family-specific fallback compatible might not be desirable, and why the > > SoC specific one is proposed? > > IIRC, it was you that wanted to use a "family-specific" fallback, I > don't understand what you want from me. If you look back at even the > context in this email, you can see you suggesting one and my counter > point. Sorry that I'm spreading my confusion around and taking up your time. I'm trying to understand if Geert's reply helped outline why a single SoC specific compatible is being used here, if so I was hoping a revised commit message would make this solution acceptable. If not I will try to summaries the issue and the different proposals so we can find a design that works and address some of the confusion before sending a new version. -- Kind Regards, Niklas Söderlund
