Re: [PATCH 1/2] dt-bindings: dmaengine: Add UniPhier external DMA controller bindings

[Kunihiko Hayashi <hayashi.kunihiko@socionext.com>]

Hi Rob,
Thank you for your comment.

On Tue, 7 Jan 2020 21:55:37 -0600 <robh@kernel.org> wrote:

> On Wed, Dec 18, 2019 at 09:56:59AM +0900, Kunihiko Hayashi wrote:
> > Add external DMA controller bindings implemented in Socionext UniPhier
> > SoCs.
> > 
> > Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> > ---
> >  .../devicetree/bindings/dma/uniphier-xdmac.txt     | 86 ++++++++++++++++++++++
> >  1 file changed, 86 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/dma/uniphier-xdmac.txt
> 
> Please make this a DT schema. See 
> Documentation/devicetree/writing-schema.rst.

Although I'm not familiar with this format, I'll try to make it.

> > 
> > diff --git a/Documentation/devicetree/bindings/dma/uniphier-xdmac.txt b/Documentation/devicetree/bindings/dma/uniphier-xdmac.txt
> > new file mode 100644
> > index 00000000..4e3927f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/dma/uniphier-xdmac.txt
> > @@ -0,0 +1,86 @@
> > +Socionext UniPhier external DMA controller bindings
> > +
> > +This describes the devicetree bindings for an external DMA engine to perform
> > +memory-to-memory or peripheral-to-memory data transfer, implemented in
> > +Socionext UniPhier SoCs.
> > +
> > +* DMA controller
> > +
> > +Required properties:
> > +- compatible: Should be "socionext,uniphier-xdmac".
> > +- reg: Specifies offset and length of the register set for the device.
> > +- interrupts: An interrupt specifier associated with the DMA controller.
> > +- #dma-cells: Must be <2>. The first cell represents the channel index.
> > +	The second cell represents the factor for transfer request.
> > +	This is mentioned in DMA client section.
> > +- dma-channels : Number of DMA channels supported. Should be 16.
> 
> If always 16, then why do you need this?

Oh, currently this means 16 or less, though, this is the number supported
by the controller. I'll fix it.

> 
> > +
> > +Example:
> > +	xdmac: dma-controller@5fc10000 {
> > +		compatible = "socionext,uniphier-xdmac";
> > +		reg = <0x5fc10000 0x1000>, <0x5fc20000 0x800>;
> > +		interrupts = <0 188 4>;
> > +		#dma-cells = <2>;
> > +		dma-channels = <16>;
> > +	};
> > +
> > +* DMA client
> > +
> > +Required properties:
> > +- dmas: A list of DMA channel requests.
> > +- dma-names: Names of the requested channels corresponding to dmas.
> > +
> > +DMA clients must use the format described in the dma.txt file, using a two cell
> > +specifier for each channel.
> 
> No need to redefine the client binding here. Just need the cell format 
> as below.

I see. I'll replace with the cell format.

Thank you,

---
Best Regards,
Kunihiko Hayashi