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

Hi Conor,

On Fri, 28 Aug 2026 at 18:21, Conor Dooley [off-list ref] wrote:

On Fri, Aug 28, 2026 at 05:59:40PM +0300, Cosmin Tanislav wrote:

quoted

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>

quoted

--- 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@linux-m68k.org

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