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SubjectRe: [PATCH 1/7] dmaengine: st_fdma: Add STMicroelectronics FDMA DT binding documentation
Hi Lee,

On Wed, 26 Aug 2015, Lee Jones wrote:

> On Tue, 25 Aug 2015, Peter Griffin wrote:
>
> > Hi Vinod,
> >
> > Thanks for reviewing.
> >
> > On Wed, 19 Aug 2015, Vinod Koul wrote:
> >
> > > On Wed, Jul 08, 2015 at 05:11:22PM +0100, Peter Griffin wrote:
> > > > This patch adds the DT binding documentation for the FDMA constroller
> > > > found on STi based chipsets from STMicroelectronics.
> > > >
> > > > Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
> > > > Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> > > > ---
> > > > Documentation/devicetree/bindings/dma/st_fdma.txt | 76 +++++++++++++++++++++++
> > > > 1 file changed, 76 insertions(+)
> > > > create mode 100644 Documentation/devicetree/bindings/dma/st_fdma.txt
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/dma/st_fdma.txt b/Documentation/devicetree/bindings/dma/st_fdma.txt
> > > > new file mode 100644
> > > > index 0000000..1ec7470
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/dma/st_fdma.txt
> > > > @@ -0,0 +1,76 @@
> > > > +* STMicroelectronics Flexible Direct Memory Access Device Tree bindings
> > > > +
> > > > +The FDMA is a general-purpose direct memory access controller capable of
> > > > +supporting 16 independent DMA channels. It accepts up to 32 DMA requests.
> > > > +The FDMA is based on a Slim processor which require a firmware.
> > > > +
> > > > +* FDMA Controller
> > > > +
> > > > +Required properties:
> > > > +- compatible : Should be "st,fdma_mpe31"
> > > > +- reg : Should contain DMA registers location and length
> > > > +- interrupts : Should contain one interrupt shared by all channel
> > >
> > > s/channel/channels
> >
> > Will fix in v2.
> >
> > >
> > > > +- dma-channels : Number of channels supported by the controller
> > > > +- #dma-cells : Must be <3>.
> > >
> > > any reason three?
> >
> > Yes, it is documented further down in the file under DMA Client.
> >
> > To make it clearer in V2 I could change to
> >
> > "- #dma-cells : Must be <3>. See DMA client section below"?
>
> - #dma-cells : Must be <3>
> 1st cell: Phandle to ... <blah>
> 2nd cell: DMA channel ... <blah>
> 3rd cell: Flags describing ... <blah>

I'd prefer not to document it twice in the same file as it is
almost 20 lines long. IMHO it makes more sense to document it under
the dma-client section like it is done presently, because when writing a
dma-client node you need to know what these things mean.

When writing a controller node all you only need to know is
"Must be <3>". A more avid reader now has a nice pointer to scroll
down if they wish to find out more.

regards,

Peter.


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