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

[Eugen.Hristev]

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@xxxxxxxxxxxxx>
>> ---
>>   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