Re: [PATCH v13 1/4] dt-bindings: dmaengine: Add doc for tegra gpcdma

[Jon Hunter]

On 30/11/2021 09:34, Jon Hunter wrote:

...

> > > > +title: NVIDIA Tegra GPC DMA Controller Device Tree Bindings
> > > > +
> > > > +description: |
> > > > +  The Tegra General Purpose Central (GPC) DMA controller is used for
> > > > +faster
> > > > +  data transfers between memory to memory, memory to device and
> > > > +device to
> > > > +  memory.
> > > > +
> > > > +maintainers:
> > > > +  - Jon Hunter <jonathanh@xxxxxxxxxx>
> > > > +  - Rajesh Gumasta <rgumasta@xxxxxxxxxx>
> > > > +
> > > > +allOf:
> > > > +  - $ref: "dma-controller.yaml#"
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    oneOf:
> > > > +      - const: nvidia,tegra186-gpcdma
> > > > +      - items:
> > > > +         - const: nvidia,tegra186-gpcdma
> > > > +         - const: nvidia,tegra194-gpcdma
> > >
> > > Still not how 'compatible' works nor what I wrote out for you.
> > I thought '186' and '194' got interchanged in your previous comment 
> > because it is 194
> > which is the superset of 186 and have got more features than 186.
> > Or probably I did not understand the idea correctly yet. 
>
> Hi Rob, this is the way around that we want it. Tegra194 is backward 
> compatible with Tegra186. The above does align with what you mentioned 
> before, so I am also not clear what the issue is with the above?


Now I think I understand. It is the order of the 'items' here that is 
key. So what we want is ...

  compatible:
    oneOf:
      - const: nvidia,tegra186-gpcdma
      - items:
         - const: nvidia,tegra194-gpcdma
         - const: nvidia,tegra186-gpcdma

At least this makes the dt_binding_check happy :-)

Jon

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nvpublic