| Message ID | 20140501063608.GA30575@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, 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. > Signed-off-by: Zhuang Jin Can <jin.can.zhuang@intel.com> > --- > drivers/usb/dwc3/gadget.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > index 70715ee..8d0c3c7 100644 > --- a/drivers/usb/dwc3/gadget.c > +++ b/drivers/usb/dwc3/gadget.c > @@ -1000,9 +1000,7 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param, > * here and stop, unmap, free and del each of the linked > * requests instead of what we do now. > */ > - usb_gadget_unmap_request(&dwc->gadget, &req->request, > - req->direction); > - list_del(&req->list); > + dwc3_gadget_giveback(dep, req, -ESHUTDOWN); > return ret; > } > > -- > 1.7.9.5 >
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.
Hi Balbi, 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 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 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. > > Signed-off-by: Zhuang Jin Can <jin.can.zhuang@intel.com> > > --- > > drivers/usb/dwc3/gadget.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > > index 70715ee..8d0c3c7 100644 > > --- a/drivers/usb/dwc3/gadget.c > > +++ b/drivers/usb/dwc3/gadget.c > > @@ -1000,9 +1000,7 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param, > > * here and stop, unmap, free and del each of the linked > > * requests instead of what we do now. > > */ > > - usb_gadget_unmap_request(&dwc->gadget, &req->request, > > - req->direction); > > - list_del(&req->list); > > + dwc3_gadget_giveback(dep, req, -ESHUTDOWN); > > return ret; > > } > > > > -- > > 1.7.9.5 > > Jincan -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Sat, May 03, 2014 at 12:05:41AM -0400, Zhuang Jin Can wrote: > On Thu, May 01, 2014 at 10:13:28AM -0500, Felipe Balbi wrote: > > 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. > > > Agree. > > > > 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. > > > I agree. I'll try to push the fix to google. alright, thanks > It's really hard to fix the race condition (for me), as any gadget or > /sys/class/udc/soft_connect can just disconnect the pullup anytime they > want. The only thing I can do is giving back the request to the > gadget if the condition happens. even in that case, gadget driver's ->disconnect() will be called and that should be enough to tell the gadget driver 'hey, don't queue anything right now because you're not talking to any host'. cheers
Hi, On Thu, May 01, 2014 at 10:13:28AM -0500, Felipe Balbi wrote: > 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. > Agree. > > 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. > I agree. I'll try to push the fix to google. It's really hard to fix the race condition (for me), as any gadget or /sys/class/udc/soft_connect can just disconnect the pullup anytime they want. The only thing I can do is giving back the request to the gadget if the condition happens. Jincan -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 70715ee..8d0c3c7 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1000,9 +1000,7 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param, * here and stop, unmap, free and del each of the linked * requests instead of what we do now. */ - usb_gadget_unmap_request(&dwc->gadget, &req->request, - req->direction); - list_del(&req->list); + dwc3_gadget_giveback(dep, req, -ESHUTDOWN); return ret; }
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. Signed-off-by: Zhuang Jin Can <jin.can.zhuang@intel.com> --- drivers/usb/dwc3/gadget.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)