RE: [PATCH 1/1] usb: chipidea: udc: workaround for endpoint conflict issue

[Peter Chen <peter.chen@nxp.com>]

 
> On 30.05.2019 9:45, Peter Chen wrote:
> 
> > An endpoint conflict occurs when the USB is working in device mode
> > during an isochronous communication. When the endpointA IN direction
> > is an isochronous IN endpoint, and the host sends an IN token to
> > endpointA on another device, then the OUT transaction may be missed
> > regardless the OUT endpoint number. Generally, this occurs when the
> > device is connected to the host through a hub and other devices are
> > connected to the same hub.
> >
> > The affected OUT endpoint can be either control, bulk, isochronous, or
> > an interrupt endpoint. After the OUT endpoint is primed, if an IN
> > token to the same endpoint number on another device is received, then
> > the OUT endpoint may be unprimed (cannot be detected by software),
> > which causes this endpoint to no longer respond to the host OUT token,
> > and thus, no corresponding interrupt occurs.
> >
> > There is no good workaround for this issue, the only thing the
> > software could do is numbering isochronous IN from the highest
> > endpoint since we have observed most of device number endpoint from the
> lowest.
> >
> > Cc: <stable@vger.kernel.org> #v3.14+
> > Cc: Jun Li <jun.li@nxp.com>
> > Signed-off-by: Peter Chen <peter.chen@nxp.com>
> > ---
> > Changes for v2:
> > - Some coding style improvements
> 
>     Nothing really changed in the patch... :-/
> 
> >   drivers/usb/chipidea/udc.c | 24 ++++++++++++++++++++++++
> >   1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> > index 829e947cabf5..411d387a45c9 100644
> > --- a/drivers/usb/chipidea/udc.c
> > +++ b/drivers/usb/chipidea/udc.c
> > @@ -1622,6 +1622,29 @@ static int ci_udc_pullup(struct usb_gadget *_gadget,
> int is_on)
> >   static int ci_udc_start(struct usb_gadget *gadget,
> >   			 struct usb_gadget_driver *driver);
> >   static int ci_udc_stop(struct usb_gadget *gadget);
> > +
> > +
> > +/* Match ISOC IN from the highest endpoint */ static struct usb_ep
> > +*ci_udc_match_ep(struct usb_gadget *gadget,
> 
>     Here...
> 
> > +			      struct usb_endpoint_descriptor *desc,
> > +			      struct usb_ss_ep_comp_descriptor *comp_desc) {
> > +	struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
> > +	struct usb_ep *ep;
> > +	u8 type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
> > +
> > +	if ((type == USB_ENDPOINT_XFER_ISOC) &&
> > +		(desc->bEndpointAddress & USB_DIR_IN)) {
> 
>     ... and here.
> 
> > +		list_for_each_entry_reverse(ep, &ci->gadget.ep_list, ep_list) {
> > +			if (ep->caps.dir_in && !ep->claimed)
> > +				return ep;
> > +		}
> > +	}
> > +
> > +	return NULL;
> > +}
> > +
> >   /**
> >    * Device operations part of the API to the USB controller hardware,
> >    * which don't involve endpoints (or i/o)
> [...]
> 

Oops. I used the former patch file. sorry about that.

Peter