Re: [PATCH 7/9] dt-bindings: iio: adc: renesas,r9a09g077-adc: document DMA support

[Conor Dooley <conor@kernel.org>]

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On Fri, Aug 28, 2026 at 07:17:00PM +0200, Geert Uytterhoeven wrote:
> Hi Conor,
> 
> On Fri, 28 Aug 2026 at 18:21, Conor Dooley <conor@kernel.org> wrote:
> > On Fri, Aug 28, 2026 at 05:59:40PM +0300, Cosmin Tanislav wrote:
> > > The ADC can transfer conversion results to memory over DMA.
> > >
> > > Allow up to three DMA specifiers, as the ADC conversion DMA request can
> > > be routed to any of the SoC's three DMA controllers.
> > >
> > > Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
> 
> > > --- a/Documentation/devicetree/bindings/iio/adc/renesas,r9a09g077-adc.yaml
> > > +++ b/Documentation/devicetree/bindings/iio/adc/renesas,r9a09g077-adc.yaml
> > > @@ -57,6 +57,18 @@ properties:
> > >        - const: adclk
> > >        - const: pclk
> > >
> > > +  dmas:
> > > +    minItems: 1
> > > +    maxItems: 3
> > > +    description:
> > > +      Must contain a list of references to DMA RX specifiers.
> > > +
> > > +  dma-names:
> > > +    minItems: 1
> > > +    maxItems: 3
> > > +    items:
> > > +      const: rx
> >
> > How does this make any sense?
> 
> Each entry provides the same functionality; the DMA core picks one that
> is available.  This was one of the design requirements when support
> for DMACs was added to DT.
> 
> > If the device can make use of three DMA controllers at once, you need 3
> > names. If it cannot, then just limit this to 1.
> 
> How do you expect that to work with multiple (the number is not fixed)
> different names?

Oh right, this shit has a specific workaround for it in dt-schema
doesn't it? Cos otherwise dma-names has a unique naming mandate.
Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

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