RE: [RFC PATCH 1/2] dt-bindings: dmaengine: xilinx_dma: Add binding for Xilinx MCDMA IP

[Radhey Shyam Pandey]

Hi Rob,

Thanks for the review. 

> -----Original Message-----
> From: Rob Herring <robh@xxxxxxxxxx>
> Sent: Tuesday, August 14, 2018 9:43 PM
> To: Radhey Shyam Pandey <radheys@xxxxxxxxxx>
> Cc: vkoul@xxxxxxxxxx; mark.rutland@xxxxxxx; Michal Simek
> <michals@xxxxxxxxxx>; dan.j.williams@xxxxxxxxx; Appana Durga Kedareswara
> Rao <appanad@xxxxxxxxxx>; lars@xxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [RFC PATCH 1/2] dt-bindings: dmaengine: xilinx_dma: Add binding
> for Xilinx MCDMA IP
> 
> On Tue, Jul 31, 2018 at 11:16:12PM +0530, Radhey Shyam Pandey wrote:
> > Add devicetree binding for Xilinx AXI Multichannel Direct Memory
> > Access (AXI MCDMA) IP. The AXI MCDMA provides high-bandwidth direct
> > memory access between memory and AXI4-Stream target peripherals. The
> > AXI MCDMA core provides scatter-gather interface with multiple channel
> support.
> >
> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt | 10
> > ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
> > b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
> > index 174af2c..57bb02e 100644
> > --- a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
> > +++ b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
> > @@ -11,9 +11,13 @@ is to receive from the device.
> >  Xilinx AXI CDMA engine, it does transfers between memory-mapped
> > source  address and a memory-mapped destination address.
> >
> > +Xilinx AXI MCDMA engine, it does transfer between memory and AXI4
> > +stream target devices. It can be configured to have up to 16
> > +independent transmit and receive channels.
> > +
> >  Required properties:
> >  - compatible: Should be "xlnx,axi-vdma-1.00.a" or "xlnx,axi-dma-1.00.a" or
> > -	      "xlnx,axi-cdma-1.00.a""
> > +	      "xlnx,axi-cdma-1.00.a" or "xlnx,axi-mcdma-1.00.a".
> 
> Please reformat to 1 per line.
Yes, I will fix it in v2.

> 
> >  - #dma-cells: Should be <1>, see "dmas" property below
> >  - reg: Should contain VDMA registers location and length.
> >  - xlnx,addrwidth: Should be the vdma addressing size in bits(ex: 32 bits).
> > @@ -56,6 +60,8 @@ Required child node properties:
> >  	For CDMA: It should be "xlnx,axi-cdma-channel".
> >  	For AXIDMA: It should be either "xlnx,axi-dma-mm2s-channel" or
> >  	"xlnx,axi-dma-s2mm-channel".
> > +	For MCDMA: It should be either "xlnx,axi-mcdma-mm2s-channel" or
> > +	"xlnx,axi-mcdma-s2mm-channel".
> 
> What's wrong with reusing the existing xlnx,axi-dma-* names?
Valid point. I think we can reuse it (Reason for adding was to follow
similar convention as of DMA , VDMA IPs).  I will address it in v2.

> 
> >  - interrupts: Should contain per channel VDMA interrupts.
> >  - xlnx,datawidth: Should contain the stream data width, take values
> >  	{32,64...1024}.
> > @@ -68,7 +74,7 @@ Optional child node properties for VDMA:
> >  	enabled/disabled in hardware.
> >  - xlnx,enable-vert-flip: Tells vertical flip is
> >  	enabled/disabled in hardware(S2MM path).
> > -Optional child node properties for AXI DMA:
> > +Optional child node properties for AXI DMA and MCDMA:	
> >  -dma-channels: Number of dma channels in child node.
> >
> >  Example:
> > --
> > 2.7.4
> >
> > --
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