linux-kernel - Re: [PATCH v1] usb: dwc3: Add error logs for unknown endpoint events

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Message-ID: <CA+zupgxGesS5MVUW6uHAzA7QzS_gq-CYQdfP+ZBVCv_2NSDVeQ@mail.gmail.com>
Date:   Wed, 3 May 2023 16:52:14 -0700
From:   Roy Luo <royluo@...gle.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "badhri@...gle.com" <badhri@...gle.com>
Subject: Re: [PATCH v1] usb: dwc3: Add error logs for unknown endpoint events

On Wed, May 3, 2023 at 4:01 PM Thinh Nguyen <Thinh.Nguyen@...opsys.com> wrote:
>
> On Wed, May 03, 2023, Roy Luo wrote:
> > In cases where the controller somehow fails to write to event buffer
> > memory (e.g. due to incorrect MMU config), the driver would receive
> > all-zero dwc3 events. However, the abnormal event is silently dropped
> > as a regular ep0out event.
>
> When it does happen, will these prints flood the dmesg log?

When this does happen, the driver cannot do the required actions to
move things forward in correspondence to the HW events (e.g.
Xfercomplete, reset, connection done, etc.).
Therefore, the controller might throw some events in the beginning but
it would cease quickly until the host does a new move that triggers
the controller to send new events.

>
> > Add error logs when an unknown endpoint event is received to highlight
> > the anamoly.
>
> anomaly?

Thanks for catching this typo, will fix it in the next patchset.

>
> >
> > Signed-off-by: Roy Luo <royluo@...gle.com>
> > ---
> >  drivers/usb/dwc3/ep0.c    | 2 ++
> >  drivers/usb/dwc3/gadget.c | 2 ++
> >  2 files changed, 4 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> > index 953b752a5052..8c9560a9999e 100644
> > --- a/drivers/usb/dwc3/ep0.c
> > +++ b/drivers/usb/dwc3/ep0.c
> > @@ -1207,5 +1207,7 @@ void dwc3_ep0_interrupt(struct dwc3 *dwc,
> >                       dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
> >               }
> >               break;
> > +     default:
> > +             dev_err(dwc->dev, "unknown endpoint event %d\n", event->endpoint_event);
>
> Can we add a break here?

Sure ,will do it in the next patchset.

>
> >       }
> >  }
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index c0ca4d12f95d..054f6f297e17 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -3803,6 +3803,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
> >               break;
> >       case DWC3_DEPEVT_RXTXFIFOEVT:
> >               break;
> > +     default:
> > +             dev_err(dwc->dev, "unknown endpoint event %d\n", event->endpoint_event);
>
> and here too.

Sure ,will do.

>
> >       }
> >  }
> >
> >
> > base-commit: c8c655c34e33544aec9d64b660872ab33c29b5f1
> > --
> > 2.40.1.495.gc816e09b53d-goog
> >
>
> Thanks,
> Thinh

Regards,
Roy Luo