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 <dig...@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
