On 16.10.2020 10:06, Vinod Koul wrote:

Hi Eugen,

On 16-10-20, 06:45, Eugen.Hristev@microchip.com wrote:

quoted

On 23.09.2020 02:33, Rob Herring wrote:

quoted

On Mon, Sep 14, 2020 at 05:09:55PM +0300, Eugen Hristev wrote:

quoted

Add optional microchip,m2m property that specifies if a controller is
dedicated to memory to memory operations only.

Signed-off-by: Eugen Hristev <redacted>
---
   Documentation/devicetree/bindings/dma/atmel-xdma.txt | 6 ++++++
   1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/dma/atmel-xdma.txt b/Documentation/devicetree/bindings/dma/atmel-xdma.txt
index 510b7f25ba24..642da6b95a29 100644
--- a/Documentation/devicetree/bindings/dma/atmel-xdma.txt
+++ b/Documentation/devicetree/bindings/dma/atmel-xdma.txt

@@ -15,6 +15,12 @@ the dmas property of client devices.
       interface identifier,
       - bit 30-24: PERID, peripheral identifier.

+Optional properties:
+- microchip,m2m: this controller is connected on AXI only to memory and it's
+     dedicated to memory to memory DMA operations. If this option is
+     missing, it's assumed that the DMA controller is connected to
+     peripherals, thus it's a per2mem and mem2per.

Wouldn't 'dma-requests = <0>' cover this case?

Rob

Hi Rob,

I do not think so. With requests = 0, it means that actually the DMA
controller is unusable ?
Since you suggest requests = 0, it means that it cannot take requests at
all ?
I do not find another example in current DT with this property set to zero.

Not really, dma-requests implies "request signals supported" which are
used for peripheral cases. m2m does not need request signals, so it is
very reasonable to conclude that dma-requests = <0> would imply no
peripheral support and only m2m support.

Thanks for explaining, I will change accordingly then.

Eugen

Thanks
--
~Vinod

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