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

[Geert Uytterhoeven]

Hi Conor,

On Fri, 28 Aug 2026 at 18:21, Conor Dooley <conor@xxxxxxxxxx> 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@xxxxxxxxxxx>

> > --- 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?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds