linux-kernel - Re: [PATCH] dt-bindings: dma: qcom,bam-dma: add optional memory interconnect properties

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Message-ID: <Y+XZflMj82Ot/UzW@matsya>
Date:   Fri, 10 Feb 2023 11:13:26 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Bhupesh Sharma <bhupesh.sharma@...aro.org>
Cc:     neil.armstrong@...aro.org,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: dma: qcom,bam-dma: add optional memory
 interconnect properties

On 09-02-23, 13:55, Bhupesh Sharma wrote:
> On 2/8/23 2:38 PM, neil.armstrong@...aro.org wrote:
> > On 08/02/2023 10:03, Krzysztof Kozlowski wrote:

> > > 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.

Is that the right approach, should the dma consumers request the
bandwidth or the dma driver. I am kind of leaning on the former

-- 
~Vinod