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
