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
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