On Mon, Aug 11, 2014 at 02:34:33PM +0200, Michael Grzeschik wrote: > Hi Peter, > > On Mon, Aug 11, 2014 at 12:56:47AM +0000, Peter Chen wrote: > > > I have seen this call is still returning EOPNOTSUPP which is also > > > returned by usb_gadget_connect and usb_gadget_disconnect if the pullup > > > function is not available. Should it not handle that case somehow special? > > > > > > > > > Is it still a valid condition to bailout if vbus is not active? > > > > > > > Hi Michael, > > > > I did this for possible pullup dp without connection (eg load gadget driver before > > vbus connect), it breaks USB spec, see 7.1.7.3 Connect and Disconnect Signaling at USB 2.0 spec. > > > > I don't know what exactly problem you met, but current pullup dp during loading > > gadget driver behavior is not suitable for webcam and android use case even vbus > > is there. > > I still work with the uvc gadget. The code in gadget/f_uvc.c calls > usb_function_deactivate. The code of uvc_function_bind will bail out in > the error code path, when the usb cable is not plugged (vbus not valid) > in that situation. I see the problem, doesn't there have problem with usb cable connected? I don't see any places can avoid pull up dp at udc-core during loading gadget driver. > > When the spec defines that calling pullup is only allowed on valid vbus, > we should somehow tell something different then EOPNOTSUPP so the caller > and that can bail out differently. > I will have a look for this problem -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
