Re: [PATCH v4 1/2] Documentation: dt: Add Xilinx zynqmp dma device tree binding documentation

[punnaiah choudary kalluri]

Hi Rob,

On Tue, Aug 25, 2015 at 12:23 AM, Rob Herring <robherring2@xxxxxxxxx> wrote:
> On Wed, Aug 5, 2015 at 10:19 PM, Punnaiah Choudary Kalluri
> <punnaiah.choudary.kalluri@xxxxxxxxxx> wrote:
>> Device-tree binding documentation for Xilinx zynqmp dma engine used in
>> Zynq UltraScale+ MPSoC.
>>
>> Signed-off-by: Punnaiah Choudary Kalluri <punnaia@xxxxxxxxxx>
>> ---
>> Changes in v4:
>> - None
>> Changes in v3:
>> - None
>> Changes in v2:
>> - None
>> ---
>>  .../devicetree/bindings/dma/xilinx/zynqmp_dma.txt  |   61 ++++++++++++++++++++
>>  1 files changed, 61 insertions(+), 0 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
>>
>> diff --git a/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt b/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
>> new file mode 100644
>> index 0000000..e4f92b9
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
>> @@ -0,0 +1,61 @@
>> +Xilinx ZynqMP DMA engine, it does support memory to memory transfers,
>> +memory to device and device to memory transfers. It also has flow
>> +control and rate control support for slave/peripheral dma access.
>> +
>> +Required properties:
>> +- compatible: Should be "xlnx,zynqmp-dma-1.0"
>> +- #dma-cells: Should be <1>, a single cell holding a line request number
>> +- reg: Memory map for module access
>> +- interrupt-parent: Interrupt controller the interrupt is routed through
>> +- interrupts: Should contain DMA channel interrupt
>> +- xlnx,bus-width: AXI buswidth in bits. Should contain 128 or 64
>> +
>> +Optional properties:
>> +- xlnx,include-sg: Indicates the controller to operate in simple or scatter
>> +                  gather dma mode
>> +- xlnx,ratectrl: Scheduling interval in terms of clock cycles for
>> +                source AXI transaction
>> +- xlnx,overfetch: Tells whether the channel is allowed to over fetch the data
>> +- xlnx,src-issue: Number of AXI outstanding transactions on source side
>> +- xlnx,desc-axi-cohrnt: Tells whether the AXI transactions generated for the
>> +                       descriptor read are marked Non-coherent
>> +- xlnx,src-axi-cohrnt: Tells whether the AXI transactions generated for the
>> +                       source descriptor payload are marked Non-coherent
>> +- xlnx,dst-axi-cohrnt: Tells whether the AXI transactions generated for the
>> +                       dst descriptor payload are marked Non-coherent
>
> Do you really need 3? dma-coherent property doesn't work for you?
>
> Not that it should dictate the binding, but the kernel doesn't support
> a device needing both coherent and non-coherent DMA ops.

I will get back to you shortly on this

>
>> +- xlnx,desc-axi-qos: AXI QOS bits to be used for descriptor fetch
>> +- xlnx,src-axi-qos: AXI QOS bits to be used for data read
>> +- xlnx,dst-axi-qos: AXI QOS bits to be used for data write
>> +- xlnx,desc-axi-cache: AXI cache bits to be used for descriptor fetch.
>> +- xlnx,desc-axi-cache: AXI cache bits to be used for data read
>> +- xlnx,desc-axi-cache: AXI cache bits to be used for data write
>
> These signals are generally part of the coherent or not setting. This
> allows for potentially invalid combinations.
>
> Plus you have a copy/paste error.

I will fix this.

Thanks,
Punnaiah
>
>> +- xlnx,src-burst-len: AXI length for data read. Support only power of 2 values
>> +                     i.e 1,2,4,8 and 16
>> +- xlnx,dst-burst-len: AXI length for data write. Support only power of 2 values
>> +                     i.e 1,2,4,8 and 16
>> +
>> +Example:
>> +++++++++
>> +fpd_dma_chan1: dma@FD500000 {
>> +       compatible = "xlnx,zynqmp-dma-1.0";
>> +       reg = <0x0 0xFD500000 0x1000>;
>> +       #dma_cells = <1>;
>> +       interrupt-parent = <&gic>;
>> +       interrupts = <0 117 4>;
>> +       xlnx,bus-width = <128>;
>> +       xlnx,include-sg;
>> +       xlnx,overfetch;
>> +       xlnx,ratectrl = <0>;
>> +       xlnx,src-issue = <16>;
>> +       xlnx,desc-axi-cohrnt;
>> +       xlnx,src-axi-cohrnt;
>> +       xlnx,dst-axi-cohrnt;
>> +       xlnx,desc-axi-qos = <0>;
>> +       xlnx,desc-axi-cache = <0>;
>> +       xlnx,src-axi-qos = <0>;
>> +       xlnx,src-axi-cache = <2>;
>> +       xlnx,dst-axi-qos = <0>;
>> +       xlnx,dst-axi-cache = <2>;
>> +       xlnx,src-burst-len = <4>;
>> +       xlnx,dst-burst-len = <4>;
>> +};
>> --
>> 1.7.4
>>
>>
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