linux-kernel - Re: [PATCH 3/3] clk: qcom: gcc-sc7280: Update the .pwrsts for usb gdsc

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Date:   Wed, 14 Sep 2022 21:23:01 +0000
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Rajendra Nayak <quic_rjendra@...cinc.com>, andersson@...nel.org,
        agross@...nel.org, konrad.dybcio@...ainline.org,
        mturquette@...libre.com, sboyd@...nel.org, johan+linaro@...nel.org,
        quic_kriskura@...cinc.com, dianders@...omium.org,
        linux-clk@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] clk: qcom: gcc-sc7280: Update the .pwrsts for usb
 gdsc

On Wed, Sep 14, 2022 at 09:12:36AM +0200, Johan Hovold wrote:
> On Thu, Sep 01, 2022 at 09:04:55AM -0700, Matthias Kaehlcke wrote:
> > On Thu, Sep 01, 2022 at 03:47:56PM +0530, Rajendra Nayak wrote:
> > > USB on sc7280 cannot support wakeups from low power states
> > > if the GDSC is turned OFF. Update the .pwrsts for usb GDSC so it
> > > only transitions to RET in low power.
> > > 
> > > Signed-off-by: Rajendra Nayak <quic_rjendra@...cinc.com>
> > 
> > Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> > Tested-by: Matthias Kaehlcke <mka@...omium.org>
> 
> Did you confirm that you actually hit the retention state?

No, how would I do that?

> IIUC, this series is equivalent to using ALWAYS_ON unless CX is actually
> powered off during suspend.

The count in /sys/kernel/debug/qcom_stats/cxsd increses with each suspend,
however it also does that with the GDSC configured as ALWAYS_ON and with
Rajendra's "arm64: dts: qcom: sc7280: Add required-opps for USB" [1], so
I guess that isn't the correct signal.

https://patchwork.kernel.org/project/linux-arm-msm/patch/20220914053017.23617-1-quic_rjendra@quicinc.com/