Hi, On Thu, May 01, 2014 at 04:44:52PM -0400, Zhuang Jin Can wrote: > On Wed, Apr 30, 2014 at 02:58:29PM -0500, Felipe Balbi wrote: > > On Thu, May 01, 2014 at 02:36:08AM -0400, Zhuang Jin Can wrote: > > > At least we should giveback the current request to the > > > gadget. Otherwise, the gadget will be stuck without knowing > > > anything. > > > > > > It was oberved that the failure can happen if the request is > > > queued when the run/stop bit of controller is not set. > > > > why is your gadget queueing any requests before calling ->udc_start() ? > > > > A better question, what modification have you done to udc-core.c which > > broke this ? udc-core *always* calls ->udc_start() by the time you load > > a gadget driver so this case will *never* happen. Whatever modification > > you did, broke this assumption and I will *not* accept this patch > > because the bug is elsewhere and *not* in mainline kernel. > > > It's found in Android using kernel 3.10.20. Android has its own > usb_composite_driver usb/gadget/android.c (not in mainline), and it so you found something on an old kernel using an out-of-tree gadget driver. > allows userspace to disconnect the pullup (i.e clear run/stop bit in dwc3) > and remove the gadget functions like adb, mtp and then add new functions > like rndis, acm. The problem is when you disconnect the pullup, a gadget > maybe in the middle of queuing a request, and result in the "start > transfer cmd failure". I think this is also a common issue for other Android gadget needs to learn how to cope with that. > usb_composite_drivers too. Normally, if one of the gadget deactivate its > own function, the pullup will be disconnected, other gadgets won't get > notified until their requests are failed. So it makes dwc3 more robust > to deal with these situations. Right, but Android gadget can run on top of several other UDCs and you want to have a single one of them cope with android's bug ? You'd be better off getting google to accept a bugfix to the android gadget, since that's where the problem lies. -- balbi
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