Felipe, On 25/01/18 18:11, Roger Quadros wrote: > Hi, > > On 24/01/18 14:19, Roger Quadros wrote: >> On 23/01/18 14:41, Roger Quadros wrote: >>> Hi Manu, >>> >>> On 23/01/18 05:45, Manu Gautam wrote: >>>> Hi, >>>> >>>> >>>> On 1/22/2018 6:31 PM, Roger Quadros wrote: >>>>> Adding/removing host/gadget controller before .pm_complete() >>>>> causes a lock-up. Let's prevent any dual-role state change >>>>> between .pm_prepare() and .pm_complete() to fix this. >>>> >>>> What kind of lock-up are you seeing? Some hardware lockup or software deadlock? >>>> IMO using a freezable_wq for drd_work should address that? >>>> >>> >>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out. >> >> using freezable_wq doesn't get rid of the deadlock. >> If I use freezable_wq plus add some delay before I do a dwc3_host_init() >> in the work function then it starts to work. >> >> As dependence on delay looks fragile so I'll stick to the current implementation >> based on .pm_prepare/complete(). >> > > So I was able to reproduce the lock up with my series as well. On further investigation > this is what I see. > > There are 2 different scenarios. > > 1) controller in host mode prior to system suspend and switches to device mode during resume. > > In this case when we call dwc3_host_exit() before tasks are thawed > xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call. > This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() function. > > > 2) controller in device mode prior to system suspend and switches to host mode during resume. > > In this case we sleep indefinitely in _dwc3_set_mode due to > dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq() > > This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor via the system_freezable_wq. > > One way I could fix this is like so. > > Felipe, could you please suggest a better way? > Maybe we need to do this in dwc3_gadget_exit() before calling usb_del_gadget_udc() ? Once you let me know your opinion I can revise this series. Thanks. > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index b417d9a..0c903c1 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work) > struct dwc3 *dwc = work_to_dwc(work); > unsigned long flags; > int ret; > + int epnum; > > if (!dwc->desired_dr_role) > return; > @@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work) > dwc3_host_exit(dwc); > break; > case DWC3_GCTL_PRTCAP_DEVICE: > + spin_lock_irqsave(&dwc->lock, flags); > + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) { > + struct dwc3_ep *dep = dwc->eps[epnum]; > + > + if (!dep) > + continue; > + > + dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING; > + } > + spin_unlock_irqrestore(&dwc->lock, flags); > + > dwc3_gadget_exit(dwc); > dwc3_event_buffers_cleanup(dwc); > break; > -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki -- 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