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From:   Jun Li <lijun.kernel@gmail.com>
Date:   Sat, 21 Mar 2020 19:05:24 +0800
Message-ID: <CAKgpwJWg8TE8-dduQ99CFK9vwgh=2AYwaPfhSN0Scoo_W-8Q8A@mail.gmail.com>
Subject: Re: [PATCH v2] usb: dwc3: support continuous runtime PM with dual role
To:     Martin Kepplinger <martin.kepplinger@puri.sm>
Cc:     Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>, rogerq@ti.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
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Jun Li <lijun.kernel@gmail.com> =E4=BA=8E2020=E5=B9=B43=E6=9C=8821=E6=97=A5=
=E5=91=A8=E5=85=AD =E4=B8=8B=E5=8D=886:59=E5=86=99=E9=81=93=EF=BC=9A
>
> Martin Kepplinger <martin.kepplinger@puri.sm> =E4=BA=8E2020=E5=B9=B43=E6=
=9C=8819=E6=97=A5=E5=91=A8=E5=9B=9B =E4=B8=8B=E5=8D=884:50=E5=86=99=E9=81=
=93=EF=BC=9A
> >
> > The DRD module calls dwc3_set_mode() on role switches, i.e. when a devi=
ce is
> > being pugged in. In order to support continuous runtime power managemen=
t when
> > plugging in / unplugging a cable, we need to call pm_runtime_get() in t=
his path.
> >
> > Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
> > ---
> >
> > revision history
> > ----------------
> > v2: move pm_rumtime calls into workqueue (thanks Roger)
> >     remove unrelated documentation patch
> > v1: https://lore.kernel.org/linux-usb/ef22f8de-9bfd-c1d5-111c-696f1336d=
bda@puri.sm/T/
> >
> >
> >  drivers/usb/dwc3/core.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 1d85c42b9c67..0c058b2ac21d 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -121,17 +121,19 @@ static void __dwc3_set_mode(struct work_struct *w=
ork)
> >         if (dwc->dr_mode !=3D USB_DR_MODE_OTG)
> >                 return;
> >
> > +       pm_runtime_get(dwc->dev);
>
> I think this needs _get_sync(), as the following mode settings may
> require runtime resumed
> to enable clocks...
>

See your v3, it's ok now.

> Li Jun
>
> > +
> >         if (dwc->current_dr_role =3D=3D DWC3_GCTL_PRTCAP_OTG)
> >                 dwc3_otg_update(dwc, 0);
> >
> >         if (!dwc->desired_dr_role)
> > -               return;
> > +               goto out;
> >
> >         if (dwc->desired_dr_role =3D=3D dwc->current_dr_role)
> > -               return;
> > +               goto out;
> >
> >         if (dwc->desired_dr_role =3D=3D DWC3_GCTL_PRTCAP_OTG && dwc->ed=
ev)
> > -               return;
> > +               goto out;
> >
> >         switch (dwc->current_dr_role) {
> >         case DWC3_GCTL_PRTCAP_HOST:
> > @@ -190,6 +192,9 @@ static void __dwc3_set_mode(struct work_struct *wor=
k)
> >                 break;
> >         }
> >
> > +out:
> > +       pm_runtime_mark_last_busy(dwc->dev);
> > +       pm_runtime_put_autosuspend(dwc->dev);
> >  }
> >
> >  void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
> > --
> > 2.20.1
> >