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From:   Jun Li <lijun.kernel@gmail.com>
Date:   Sat, 21 Mar 2020 18:59:17 +0800
Message-ID: <CAKgpwJXyt1O_J2HR5uHgAg3JTcwxSrOBPg7JcLnVyo-K9QRE8g@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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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 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 thi=
s 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-696f1336dbd=
a@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 *wor=
k)
>         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...

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->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
>