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() ? 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