Messages in this thread | | | Date | Thu, 9 Feb 2023 13:55:44 +0530 | Subject | Re: [PATCH] dt-bindings: dma: qcom,bam-dma: add optional memory interconnect properties | From | Bhupesh Sharma <> |
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On 2/8/23 2:38 PM, neil.armstrong@linaro.org wrote: > On 08/02/2023 10:03, Krzysztof Kozlowski wrote: >> On 07/02/2023 16:27, Dmitry Baryshkov wrote: >>> On 07/02/2023 15:35, Neil Armstrong wrote: >>>> On 07/02/2023 11:32, Dmitry Baryshkov wrote: >>>>> On 07/02/2023 12:03, Neil Armstrong wrote: >>>>>> Recents SoCs like the SM8450 or SM8550 requires memory interconnect >>>>>> in order to have functional DMA. >>>>>> >>>>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org> >>>>>> --- >>>>>> Documentation/devicetree/bindings/dma/qcom,bam-dma.yaml | 6 ++++++ >>>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> I suspect this will not work without a change for a driver. >>>>> >>>> >>>> I had the impression single interconnect entries would be taken in >>>> account >>>> by the platform core, but it doesn't seem to be the case, anyway I >>>> can;t >>>> find >>>> any code doing that. >>> >>> Probably you mixed interconnects and power-domains here. >>> >> >> The driver change was submitted some time ago: >> https://lore.kernel.org/all/20210505213731.538612-10-bhupesh.sharma@linaro.org/ >> >> There is already DTS user of it and we expect driver to be resubmitted >> at some point. >> >> What I don't really get is that crypto driver sets bandwidth for >> interconnects, not the BAM. Why BAM needs interconnect? Usually you do >> not need to initialize some middle paths. Getting the final interconnect >> path (e.g. crypto-memory) is enough, because it includes everything in >> between. > > Indeed the interconnect on BAM may be redundant since QCE sets the BW, > I'll investigate to understand if it's also necessary on BAM.
Since we are already doing this via QCE driver (since crypto block on qcom SoCs employs BAM DMA services) via [1], this change is not needed for sm8150, sm8250, sm8350 and subsequent qcom SoCs (available presently), so this patch can be dropped.
[1]. https://www.spinics.net/lists/linux-arm-msm/msg142957.html
Thanks, Bhupesh
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