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. 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. Thanks, Michael -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- 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
