linux-kernel - Re: [PATCH v2] usb: dwc3: support continuous runtime PM with dual role

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Message-ID: <CAKgpwJWg8TE8-dduQ99CFK9vwgh=2AYwaPfhSN0Scoo_W-8Q8A@mail.gmail.com>
Date:   Sat, 21 Mar 2020 19:05:24 +0800
From:   Jun Li <lijun.kernel@...il.com>
To:     Martin Kepplinger <martin.kepplinger@...i.sm>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>, rogerq@...com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: dwc3: support continuous runtime PM with dual role

Jun Li <lijun.kernel@...il.com> 于2020年3月21日周六 下午6:59写道：
>
> Martin Kepplinger <martin.kepplinger@...i.sm> 于2020年3月19日周四 下午4:50写道：
> >
> > The DRD module calls dwc3_set_mode() on role switches, i.e. when a device is
> > being pugged in. In order to support continuous runtime power management when
> > plugging in / unplugging a cable, we need to call pm_runtime_get() in this path.
> >
> > Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.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-696f1336dbda@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 *work)
> >         if (dwc->dr_mode != 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 == DWC3_GCTL_PRTCAP_OTG)
> >                 dwc3_otg_update(dwc, 0);
> >
> >         if (!dwc->desired_dr_role)
> > -               return;
> > +               goto out;
> >
> >         if (dwc->desired_dr_role == dwc->current_dr_role)
> > -               return;
> > +               goto out;
> >
> >         if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev)
> > -               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 *work)
> >                 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
> >