Re: [PATCH 6/7] dt-bindings: dmaengine: at_xdmac: add optional microchip,m2m property

Eugen.Hristev
2020-10-16T06:45:56Z

On 23.09.2020 02:33, Rob Herring wrote:

> On Mon, Sep 14, 2020 at 05:09:55PM +0300, Eugen Hristev wrote:
>> Add optional microchip,m2m property that specifies if a controller is
>> dedicated to memory to memory operations only.
>>
>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>> ---
>> 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.

Eugen