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

[Wesley Cheng]

Hi Thinh,

On 7/8/2022 6:58 PM, Thinh Nguyen wrote:
> On 7/8/2022, 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.
> >
> > Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> > ---
> >    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;
> > -		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 bd40608b19df..fba2797ad9ae 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -3696,8 +3696,10 @@ 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;
> > +
> >    	if (!(dep->flags & DWC3_EP_TRANSFER_STARTED) ||
> > -	    (dep->flags & DWC3_EP_DELAY_STOP) ||
> >    	    (dep->flags & DWC3_EP_END_TRANSFER_PENDING))
> >    		return;
> >    
> > @@ -3744,6 +3746,7 @@ void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
> >    	__dwc3_stop_active_transfer(dep, force, interrupt);
> >    	spin_lock(&dwc->lock);
> >    
> > +	dep->flags &= ~DWC3_EP_DELAY_STOP;
>
> Can we clear this flag in __dwc3_stop_active_transfer(). It should apply
> if End Transfer command was sent.

I wanted to make sure that we weren't modifying the DEP flags outside of 
a spin lock.  Patch#3 modifies it where we unlock before calling 
__dwc3_stop_active_transfer(), so we can allow the dwc3 threaded IRQ 
handle events while the cmd status polling happens.

Maybe we can unlock/lock the dwc3->lock inside 
__dwc3_stop_active_transfer() and that way we can ensure DEP flags are 
modified properly?

Thanks
Wesley Cheng