linux-kernel - Re: [PATCH] usb: dwc3: Properly handle processing of pending events

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Message-ID: <2bf3663abc72448da44427dcaedb49fe@shmbx05.spreadtrum.com>
Date:   Wed, 2 Aug 2023 01:39:09 +0000
From:   庞苏荣 (Surong Pang) 
        <surong.pang@...soc.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Elson Roy Serrao <quic_eserrao@...cinc.com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>,
        "rogerq@...nel.org" <rogerq@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        庞苏荣 (Surong Pang) 
        <surong.pang@...soc.com>
Subject: Re: [PATCH] usb: dwc3: Properly handle processing of pending events

Dears，
If there is/are event(s) in evt->buf,  in dwc3_check_event_buf,  dwc3_thread_interrupt will be woke up.

> > @@ -4718,6 +4723,8 @@ void dwc3_gadget_process_pending_events(struct
> > dwc3 *dwc)  {
> >       if (dwc->pending_events) {
> >               dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
> > +             dwc3_thread_interrupt(dwc->irq_gadget, dwc->ev_buf);
> > +             pm_runtime_put(dwc->dev);
> >               dwc->pending_events = false;
> >               enable_irq(dwc->irq_gadget);
> >       }

I just want to know dwc3_thread_interrupt here is necessary or not?


> On Tue, Aug 02, 2023 8:12 Thinh Nguyen wrote:
>> On Tue, Aug 01, 2023, Elson Roy Serrao wrote:
> > If dwc3 is runtime suspended we defer processing the event buffer
> > until resume, by setting the pending_events flag. Set this flag before
> > triggering resume to avoid race with the runtime resume callback.
> >
> > While handling the pending events, in addition to checking the event
> > buffer we also need to process it. Handle this by explicitly calling
> > dwc3_thread_interrupt(). Also balance the runtime pm get() operation
> > that triggered this processing.
> >
> > Cc: stable@...r.kernel.org
> > Fixes: fc8bb91bc83e ("usb: dwc3: implement runtime PM")
> > Signed-off-by: Elson Roy Serrao <quic_eserrao@...cinc.com>
> > ---
> > Change separated from below series as an independent fix based on the
> > earlier discussion
> > https://urldefense.com/v3/__https://lore.kernel.org/all/be57511d-2005-
> > a1f5-d5a5-809e71029aec@...cinc.com/__;!!A4F2R9G_pg!YtZ93ALEpDNTCEhf0WE
> > yB5S090pPlKIKVtjqTOAEJdxdWbl8QG6eiRmlvfivUtD5qjKWWLX2C4fb4W8VAg5w9qasL
> > uKB$
> >
> >  drivers/usb/dwc3/gadget.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 5fd067151fbf..858fe4c299b7 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -4455,9 +4455,14 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
> >       u32 count;
> >
> >       if (pm_runtime_suspended(dwc->dev)) {
> > +             dwc->pending_events = true;
> > +             /*
> > +              * Trigger runtime resume. The get() function will be balanced
> > +              * after processing the pending events in dwc3_process_pending
> > +              * events().
> > +              */
> >               pm_runtime_get(dwc->dev);
> >               disable_irq_nosync(dwc->irq_gadget);
> > -             dwc->pending_events = true;
> >               return IRQ_HANDLED;
> >       }
> >
> > @@ -4718,6 +4723,8 @@ void dwc3_gadget_process_pending_events(struct
> > dwc3 *dwc)  {
> >       if (dwc->pending_events) {
> >               dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
> > +             dwc3_thread_interrupt(dwc->irq_gadget, dwc->ev_buf);
> > +             pm_runtime_put(dwc->dev);
> >               dwc->pending_events = false;
> >               enable_irq(dwc->irq_gadget);
> >       }
> > --
> > 2.17.1
> >
> 
> This fix is more complete.
> 
> Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
> 
> Thanks,
> Thinh