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.
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