Re: [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:

quoted

Hi Vinod,

Thanks for reviewing.

On Wed, 19 Aug 2015, Vinod Koul wrote:

quoted

On Wed, Jul 08, 2015 at 05:11:22PM +0100, Peter Griffin wrote:

quoted

This patch adds the DT binding documentation for the FDMA constroller
found on STi based chipsets from STMicroelectronics.

Signed-off-by: Ludovic Barre <redacted>
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.

quoted

quoted

+- 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.