| Message ID | 20200914140956.221432-7-eugen.hristev@microchip.com |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | dmaengine: add support for sama7g5 based at_xdmac | expand |
| Context | Check | Description |
|---|---|---|
| robh/checkpatch | success |
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
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
Hi Eugen, On 16-10-20, 06:45, Eugen.Hristev@microchip.com wrote: > 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. 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
On 16.10.2020 10:06, Vinod Koul wrote: > Hi Eugen, > > On 16-10-20, 06:45, Eugen.Hristev@microchip.com wrote: >> 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. > > 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 >
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. + Example: dma1: dma-controller@f0004000 {
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(+)