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

[punnaiah choudary kalluri]

On Tue, Aug 25, 2015 at 12:16 PM, punnaiah choudary kalluri
<punnaia@xxxxxxxxxx> wrote:
> 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

Yes. dma-coherent property works. I will modify the bindings.

Thanks,
Punnaiah
>
>>
>>> +- 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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