Re: [PATCH v2 4/5] usb: dwc3: Allow end transfer commands to be sent during soft disconnect

[Wesley Cheng]

Hi Thinh,

On 7/21/2022 3:08 PM, Thinh Nguyen wrote:
> Hi Wesley,
>
> On 7/12/2022, Wesley Cheng wrote:
> > If soft disconnect is in progress, allow the endxfer command to be sent,
> > without this, there is an issue where the stop active transfer call
> > (during pullup disable) wouldn't actually issue the endxfer command,
> > while clearing the DEP flag.
> >
> > In addition, if the DWC3_EP_DELAY_STOP flag was set before soft disconnect
> > started (i.e. from the dequeue path), ensure that when the EP0 transaction
> > completes during soft disconnect, to issue the endxfer with the force
> > parameter set, as it does not expect a command complete event.
> >
> > Fixes: e4cf6580ac740 ("usb: dwc3: gadget: Wait for ep0 xfers to complete during dequeue")
> > Suggested-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
> > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > ---
> > Link:
> >     https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/1a1a5485-790e-79ce-f5a6-1e96d9b49a47@xxxxxxxxxxxx/__;!!A4F2R9G_pg!cXW2TlALYWnXNPg-NoMFUrQ8K1egEZiQizZ5CA1DOM1Gcw4tfOULy-_2eMGvL8pQPte5dScFON-0wxH2eXu8ijEQUbs$
> >
> >    drivers/usb/dwc3/ep0.c    | 3 +--
> >    drivers/usb/dwc3/gadget.c | 5 ++++-
> >    2 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> > index 506ef717fdc0..5851b0e9db0a 100644
> > --- a/drivers/usb/dwc3/ep0.c
> > +++ b/drivers/usb/dwc3/ep0.c
> > @@ -290,8 +290,7 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
> >    		if (!(dwc3_ep->flags & DWC3_EP_DELAY_STOP))
> >    			continue;
> >    
> > -		dwc3_ep->flags &= ~DWC3_EP_DELAY_STOP;
>
> If we don't clear this flag here,

This is why I added the dwc->connected argument to control the 
"interrupt" argument.

> > -		dwc3_stop_active_transfer(dwc3_ep, true, true);
> > +		dwc3_stop_active_transfer(dwc3_ep, true, dwc->connected);
> >    	}
> >    }
> >    
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index ee85b773e3fe..41b7007358de 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -1693,6 +1693,7 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
> >    		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
> >    	else if (!ret)
> >    		dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
> > +	dep->flags &= ~DWC3_EP_DELAY_STOP;
> >    
> >    	return ret;
> >    }
> > @@ -3686,8 +3687,10 @@ void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
> >    	if (dep->number <= 1 && dwc->ep0state != EP0_DATA_PHASE)
> >    		return;
> >    
> > +	if (interrupt && (dep->flags & DWC3_EP_DELAY_STOP))
> > +		return;
> > +
>
> then it may not go through here. I think I made this same mistake in my
> previous suggestion.

Since dwc->connected is set to FALSE before we call stop active 
transfers, if we ever run into a situation where delayed stop is set 
already, then it should go through.

Thanks
Wesley Cheng