linux-kernel - Re: [PATCH] arm64: dts: qcom: sc7180: Add sleep state for alc5682 codec

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Date:   Thu, 18 Aug 2022 15:19:37 -0700
From:   "Joseph S. Barrera III" <joebar@...omium.org>
To:     Doug Anderson <dianders@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>
Cc:     linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Alexandru Stan <amstan@...omium.org>,
        Judy Hsiao <judyhsiao@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: qcom: sc7180: Add sleep state for alc5682
 codec

On 8/18/22 1:34 PM, Doug Anderson wrote:
> I tend to agree with Stephen's analysis. We actually need to keep the
> pullup enabled unless we are actually turning power off to the codec,
> which we don't seem to be doing.
> 
> I guess I'm a little surprised that we don't even seem to turn any of
> this codec's regulators off in S3. That seems like it would be drawing
> power that we don't want. Maybe the "low power" mode of the codec is
> low enough and we need to avoid powering it off to avoid pops / hisses
> in S3 or something? If that's true, this might be one of those places
> where the "LPM" of the regulators might actually be useful...

OK, fair enough, so suggestions on what I should do instead? Should I
look at why or how to turn the regulators off? Should I look into LPM?
Are there existing bugs for such work?