RE: [PATCH v4] usb: dwc2/gadget: rework disconnect event handling

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> From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of Felipe Balbi
> Sent: Friday, November 14, 2014 11:05 AM
> 
> On Fri, Nov 14, 2014 at 07:01:37PM +0000, Paul Zimmerman wrote:
> > > -----Original Message-----
> > > From: Marek Szyprowski [mailto:m.szyprowski@xxxxxxxxxxx]
> > > Sent: Friday, November 14, 2014 4:20 AM
> > >
> > > This patch adds a call to s3c_hsotg_disconnect() from 'end session'
> > > interrupt (GOTGINT_SES_END_DET) to correctly notify gadget subsystem
> > > about unplugged usb cable. DISCONNINT interrupt cannot be used for this
> > > purpose, because it is asserted only in host mode.
> > >
> > > To avoid reporting disconnect event more than once, a disconnect call has
> > > been moved from USB_REQ_SET_ADDRESS handling function to SESSREQINT
> > > interrupt. This way driver ensures that disconnect event is reported
> > > either when usb cable is unplugged or every time the host starts a new
> > > session.
> > >
> > > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > > ---
> > >  drivers/usb/dwc2/core.h   |  1 +
> > >  drivers/usb/dwc2/gadget.c | 13 +++++++++++--
> > >  2 files changed, 12 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> > > index 55c90c53f2d6..78b9090ebf71 100644
> > > --- a/drivers/usb/dwc2/core.h
> > > +++ b/drivers/usb/dwc2/core.h
> > > @@ -210,6 +210,7 @@ struct s3c_hsotg {
> > >  	u8                      ctrl_buff[8];
> > >
> > >  	struct usb_gadget       gadget;
> > > +	unsigned int		session:1;
> > >  	unsigned int            setup;
> > >  	unsigned long           last_rst;
> > >  	struct s3c_hsotg_ep     *eps;
> > > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> > > index fcd2bb55ccca..c7f68dc1cf6b 100644
> > > --- a/drivers/usb/dwc2/gadget.c
> > > +++ b/drivers/usb/dwc2/gadget.c
> > > @@ -1029,7 +1029,6 @@ static int s3c_hsotg_process_req_feature(struct s3c_hsotg *hsotg,
> > >  }
> > >
> > >  static void s3c_hsotg_enqueue_setup(struct s3c_hsotg *hsotg);
> > > -static void s3c_hsotg_disconnect(struct s3c_hsotg *hsotg);
> > >
> > >  /**
> > >   * s3c_hsotg_stall_ep0 - stall ep0
> > > @@ -1107,7 +1106,6 @@ static void s3c_hsotg_process_control(struct s3c_hsotg *hsotg,
> > >  	if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD) {
> > >  		switch (ctrl->bRequest) {
> > >  		case USB_REQ_SET_ADDRESS:
> > > -			s3c_hsotg_disconnect(hsotg);
> > >  			dcfg = readl(hsotg->regs + DCFG);
> > >  			dcfg &= ~DCFG_DEVADDR_MASK;
> > >  			dcfg |= (le16_to_cpu(ctrl->wValue) <<
> > > @@ -2031,6 +2029,10 @@ static void s3c_hsotg_disconnect(struct s3c_hsotg *hsotg)
> > >  {
> > >  	unsigned ep;
> > >
> > > +	if (!hsotg->session)
> > > +		return;
> > > +
> > > +	hsotg->session = 0;
> > >  	for (ep = 0; ep < hsotg->num_of_eps; ep++)
> > >  		kill_all_requests(hsotg, &hsotg->eps[ep], -ESHUTDOWN, true);
> > >
> > > @@ -2290,11 +2292,18 @@ irq_retry:
> > >  		dev_info(hsotg->dev, "OTGInt: %08x\n", otgint);
> > >
> > >  		writel(otgint, hsotg->regs + GOTGINT);
> > > +
> > > +		if (otgint & GOTGINT_SES_END_DET) {
> > > +			s3c_hsotg_disconnect(hsotg);
> >
> > I think you should clear hsotg->session here, shouldn't you?
> > Otherwise I think s3c_hsotg_disconnect() will be called twice, once
> > here and once when the next GINTSTS_SESSREQINT comes.
> 
> the best way to avoid that would be fiddle with hsotg->session inside
> s3c_hsotg_disconnect() only.

Whoops, I just noticed that hsotg->session *is* cleared inside of
s3c_hsotg_disconnect(). So I think the patch is good as-is.

Acked-by: Paul Zimmerman <paulz@xxxxxxxxxxxx>

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