RE: [PATCH v3] usb: dwc2/gadget: report disconnect event from 'end session' irq

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> From: Marek Szyprowski [mailto:m.szyprowski@xxxxxxxxxxx]
> Sent: Thursday, November 13, 2014 5:40 AM
> 
> On 2014-10-31 19:15, Paul Zimmerman wrote:
> >> From: Marek Szyprowski [mailto:m.szyprowski@xxxxxxxxxxx]
> >> Sent: Friday, October 31, 2014 1:04 AM
> >> To: linux-usb@xxxxxxxxxxxxxxx; linux-samsung-soc@xxxxxxxxxxxxxxx
> >> Cc: Marek Szyprowski; Kyungmin Park; Robert Baldyga; Paul Zimmerman; Krzysztof Kozlowski; Felipe
> Balbi
> >> Subject: [PATCH v3] usb: dwc2/gadget: report disconnect event from 'end session' irq
> >>
> >> 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. 'disconnected' interrupt (DISCONNINT) might
> >> look a bit more suitable for this event, but it is asserted only in
> >> host mode, so in device mode we need to use something else.
> >>
> >> Additional check has been added in s3c_hsotg_disconnect() function
> >> to ensure that the event is reported only once after successful device
> >> enumeration.
> >>
> >> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> >> ---
> >>   drivers/usb/dwc2/core.h   |  1 +
> >>   drivers/usb/dwc2/gadget.c | 10 ++++++++++
> >>   2 files changed, 11 insertions(+)
> >>
> >> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> >> index 55c90c53f2d6..b42df32e7737 100644
> >> --- a/drivers/usb/dwc2/core.h
> >> +++ b/drivers/usb/dwc2/core.h
> >> @@ -212,6 +212,7 @@ struct s3c_hsotg {
> >>   	struct usb_gadget       gadget;
> >>   	unsigned int            setup;
> >>   	unsigned long           last_rst;
> >> +	unsigned int		address;
> >>   	struct s3c_hsotg_ep     *eps;
> >>   };
> >>
> >> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> >> index fcd2bb55ccca..6304efba11aa 100644
> >> --- a/drivers/usb/dwc2/gadget.c
> >> +++ b/drivers/usb/dwc2/gadget.c
> >> @@ -1114,6 +1114,7 @@ static void s3c_hsotg_process_control(struct s3c_hsotg *hsotg,
> >>   				 DCFG_DEVADDR_SHIFT) & DCFG_DEVADDR_MASK;
> >>   			writel(dcfg, hsotg->regs + DCFG);
> >>
> >> +			hsotg->address = ctrl->wValue;
> >>   			dev_info(hsotg->dev, "new address %d\n", ctrl->wValue);
> >>
> >>   			ret = s3c_hsotg_send_reply(hsotg, ep0, NULL, 0);
> >> @@ -2031,6 +2032,10 @@ static void s3c_hsotg_disconnect(struct s3c_hsotg *hsotg)
> >>   {
> >>   	unsigned ep;
> >>
> >> +	if (!hsotg->address)
> >> +		return;
> >> +
> >> +	hsotg->address = 0;
> >>   	for (ep = 0; ep < hsotg->num_of_eps; ep++)
> >>   		kill_all_requests(hsotg, &hsotg->eps[ep], -ESHUTDOWN, true);
> >>
> >> @@ -2290,6 +2295,11 @@ 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);
> >> +			hsotg->gadget.speed = USB_SPEED_UNKNOWN;
> >> +		}
> >>   	}
> >>
> >>   	if (gintsts & GINTSTS_SESSREQINT) {
> > I don't think this is right. The host can send control requests to
> > the device before it sends a SetAddress to change from the default
> > address of 0. So if a GOTGINT_SES_END_DET happens before the
> > SetAddress, it will be ignored.
> >
> > Or am I missing something?
> 
> Well, right. However before finishing enumeration (setting the address)
> host usually
> only retrieves some usb descriptors what doesn't change the state of the
> gadget.
> Right now we always reported 'disconnected' event before setting the new
> address,
> what is a bit overkill (in some cases gadget driver got this even more
> than once).
> The above code handles all cases correctly and reports disconnect event
> only once.

Well, if the disconnect happens before the SetAddress, the disconnect
won't be reported at all. Unless I'm reading the code wrong.

-- 
Paul

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