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Re: [PATCH 1/3] Documentation: dt: iio: at91-sama5d2_adc: add optional dma property

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  Re: [PATCH 1/3] Documentation: dt: iio: at91-sama5d2_adc: add  optional dma property Rob Herring <robh@kernel.org> - 2017-08-17 17:20 +0200
    Re: [PATCH 1/3] Documentation: dt: iio: at91-sama5d2_adc: add  optional dma property Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2017-08-24 14:00 +0200

#1714123 — Re: [PATCH 1/3] Documentation: dt: iio: at91-sama5d2_adc: add optional dma property

On Thu, Aug 10, 2017 at 03:34:57PM +0300, Eugen Hristev wrote:
> Added property for DMA configuration of the device.

"dt-bindings: iio: ..." is preferred for subject.

> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> index 552e7a8..5f94d47 100644
> --- a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> @@ -17,6 +17,11 @@ Required properties:
>    This property uses the IRQ edge types values: IRQ_TYPE_EDGE_RISING ,
>    IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH
>  
> +Optional properties:
> +  - dmas: Phandle to dma channel for the ADC.
> +  See ../../dma/dma.txt for details.
> +  - dma-names: Must be "rx" when dmas property is being used.

*-names is pointless when there's only one.

> +
>  Example:
>  
>  adc: adc@fc030000 {
> @@ -31,4 +36,6 @@ adc: adc@fc030000 {
>  	vddana-supply = <&vdd_3v3_lp_reg>;
>  	vref-supply = <&vdd_3v3_lp_reg>;
>  	atmel,trigger-edge-type = <IRQ_TYPE_EDGE_BOTH>;
> +	dmas = <&dma0 (AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1) | AT91_XDMAC_DT_PERID(25))>;
> +	dma-names = "rx";
>  }
> -- 
> 2.7.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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#1719177

On 17/08/2017 at 10:10:59 -0500, Rob Herring wrote:
> On Thu, Aug 10, 2017 at 03:34:57PM +0300, Eugen Hristev wrote:
> > Added property for DMA configuration of the device.
> 
> "dt-bindings: iio: ..." is preferred for subject.
> 
> > 
> > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> > ---
> >  Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > index 552e7a8..5f94d47 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > +++ b/Documentation/devicetree/bindings/iio/adc/at91-sama5d2_adc.txt
> > @@ -17,6 +17,11 @@ Required properties:
> >    This property uses the IRQ edge types values: IRQ_TYPE_EDGE_RISING ,
> >    IRQ_TYPE_EDGE_FALLING or IRQ_TYPE_EDGE_BOTH
> >  
> > +Optional properties:
> > +  - dmas: Phandle to dma channel for the ADC.
> > +  See ../../dma/dma.txt for details.
> > +  - dma-names: Must be "rx" when dmas property is being used.
> 
> *-names is pointless when there's only one.
> 

Hypothetical question: what if at some point we have multiple dmas? Then
we would have the choice between breaking the backward compatibility or
handling the absence of dma-names in the driver which is less than
ideal.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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