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Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB DMA controller

From Jon Hunter <jonathanh@nvidia.com>
Newsgroups linux.kernel
Subject Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB DMA controller
Date 2017-09-27 15:50 +0200
Message-ID <uukSS-3A0-21@gated-at.bofh.it> (permalink)
References (2 earlier) <utZv3-66l-11@gated-at.bofh.it> <uu9NN-4b6-15@gated-at.bofh.it> <uug2S-8no-19@gated-at.bofh.it> <uujtN-2gN-37@gated-at.bofh.it> <uukSR-3A0-1@gated-at.bofh.it>
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On 27/09/17 14:44, Jon Hunter wrote:
> 
> On 27/09/17 13:12, Dmitry Osipenko wrote:
>> On 27.09.2017 11:34, Jon Hunter wrote:
>>>
>>> On 27/09/17 02:57, Dmitry Osipenko wrote:
>>>> On 26.09.2017 17:50, Jon Hunter wrote:
>>>>>
>>>>> On 26/09/17 00:22, Dmitry Osipenko wrote:
>>>>>> Document DT bindings for NVIDIA Tegra AHB DMA controller that presents
>>>>>> on Tegra20/30 SoC's.
>>>>>>
>>>>>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>>>>>> ---
>>>>>>  .../bindings/dma/nvidia,tegra20-ahbdma.txt         | 23 ++++++++++++++++++++++
>>>>>>  1 file changed, 23 insertions(+)
>>>>>>  create mode 100644 Documentation/devicetree/bindings/dma/nvidia,tegra20-ahbdma.txt
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/dma/nvidia,tegra20-ahbdma.txt b/Documentation/devicetree/bindings/dma/nvidia,tegra20-ahbdma.txt
>>>>>> new file mode 100644
>>>>>> index 000000000000..2af9aa76ae11
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/dma/nvidia,tegra20-ahbdma.txt
>>>>>> @@ -0,0 +1,23 @@
>>>>>> +* NVIDIA Tegra AHB DMA controller
>>>>>> +
>>>>>> +Required properties:
>>>>>> +- compatible:	Must be "nvidia,tegra20-ahbdma"
>>>>>> +- reg:		Should contain registers base address and length.
>>>>>> +- interrupts:	Should contain one entry, DMA controller interrupt.
>>>>>> +- clocks:	Should contain one entry, DMA controller clock.
>>>>>> +- resets :	Should contain one entry, DMA controller reset.
>>>>>> +- #dma-cells:	Should be <1>. The cell represents DMA request select value
>>>>>> +		for the peripheral. For more details consult the Tegra TRM's
>>>>>> +		documentation, in particular AHB DMA channel control register
>>>>>> +		REQ_SEL field.
>>>>>
>>>>> What about the TRIG_SEL field? Do we need to handle this here as well?
>>>>>
>>>>
>>>> Actually, DMA transfer trigger isn't related a hardware description. It's up to
>>>> software to decide what trigger to select. So it shouldn't be in the binding.
>>>
>>> I think it could be, if say a board wanted a GPIO to trigger a transfer.
>>>
>>
>> GPIO isn't a very good example, there is no "GPIO" trigger. To me all triggers
>> are software-defined, so that software could create transfer chains.
> 
> TRM shows the following in the APBDMA_TRIG_REG_0 ...
> 
> "XRQ_A: XRQ.A (GPIOA) (Hardware initiated DMA request)"

Furthermore there are timer and hw-semaphore triggers as well.

Jon

-- 
nvpublic

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Thread

Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-27 04:00 +0200
  Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Jon Hunter <jonathanh@nvidia.com> - 2017-09-27 10:40 +0200
    Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-27 14:20 +0200
      Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Jon Hunter <jonathanh@nvidia.com> - 2017-09-27 15:50 +0200
        Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Jon Hunter <jonathanh@nvidia.com> - 2017-09-27 15:50 +0200
          Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-27 16:30 +0200
    Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Stephen Boyd <sboyd@codeaurora.org> - 2017-09-28 01:40 +0200
      Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Jon Hunter <jonathanh@nvidia.com> - 2017-09-28 10:40 +0200
    Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Stephen Warren <swarren@wwwdotorg.org> - 2017-09-29 21:40 +0200
      Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-30 05:20 +0200
        Re: [PATCH v1 3/5] dt-bindings: Add DT bindings for NVIDIA Tegra AHB  DMA controller Stephen Warren <swarren@wwwdotorg.org> - 2017-10-02 22:50 +0200

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