linux-kernel - Re: [PATCH 2/2] clk: qcom: gcc-sc7280: Keep USB GDSC power domains on when USB wakeup is enabled

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Message-ID: <YwjGpSXOscDwbvQH@hovoldconsulting.com>
Date:   Fri, 26 Aug 2022 15:12:05 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Krishna Kurapati <quic_kriskura@...cinc.com>,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH 2/2] clk: qcom: gcc-sc7280: Keep USB GDSC power domains
 on when USB wakeup is enabled

On Fri, Aug 26, 2022 at 06:05:19AM -0700, Matthias Kaehlcke wrote:
> On Thu, Aug 25, 2022 at 03:16:58PM -0700, Matthias Kaehlcke wrote:
> > On Wed, Aug 24, 2022 at 10:47:44AM +0200, Johan Hovold wrote:

> > > The wakeup setting doesn't seem to have anything to do with the genpd
> > > issues on sc8280xp and the controller doesn't resume properly regardless
> > > of whether the PHYs have been disabled or not during suspend unless the
> > > PD is left on.
> > 
> > I'm essentially seeing the same. USB is hosed after resume unless the PD
> > is left on.
> > 
> > On Chrome OS we currently work around that with a version of commit
> > d9be8d5c5b03 ("usb: dwc3: qcom: Keep power domain on to retain controller
> > status") which was reverted upstream. I'm not sure whether USB worked after
> > resume before we enabled wakeup support. I would have sworn it did, but we
> > landed an old version of the wakeup patches a long time ago, so my
> > memory might be failing me.
> 
> I need to remind myself that keeping the GDSC on is only needed when the PHYs
> are kept on. The PHYs were always off before wakeup support was added, which
> is why USB wasn't broken after suspend in the pre-wakeup days.

Ok, so to be clear: if you disable wakeup with my patches applied so
that the PD is actually turned off, USB still resumes with only
GENPD_FLAG_ACTIVE_WAKEUP set?

That is, you don't need to set ALWAYS_ON as I do with sc8280xp?

Johan