On 10/13/2015 9:05 AM, Felipe Balbi wrote:
>
> Hi,
>
> John Youn <John.Youn@xxxxxxxxxxxx> writes:
>> On 10/12/2015 12:25 PM, Felipe Balbi wrote:
>>> This reverts commit 70f3a9caa11665e9f9aace581d85d8483716a4c8.
>>>
>>> That commit was causing a lockdep splat with g_ether and that
>>> was interfering with proper functionality.
>>>
>>> Signed-off-by: Felipe Balbi <balbi@xxxxxx>
>>> ---
>>> drivers/usb/dwc3/gadget.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index cca806e09e5b..81bfb9ad1e2e 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -2642,15 +2642,16 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3 *dwc, u32 buf)
>>> static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc)
>>> {
>>> struct dwc3 *dwc = _dwc;
>>> + unsigned long flags;
>>> irqreturn_t ret = IRQ_NONE;
>>> int i;
>>>
>>> - spin_lock(&dwc->lock);
>>> + spin_lock_irqsave(&dwc->lock, flags);
>>>
>>> for (i = 0; i < dwc->num_event_buffers; i++)
>>> ret |= dwc3_process_event_buf(dwc, i);
>>>
>>> - spin_unlock(&dwc->lock);
>>> + spin_unlock_irqrestore(&dwc->lock, flags);
>>>
>>> return ret;
>>> }
>>>
>>
>> Hi Felipe,
>>
>> This seems related to a problem we've been tracking down the past
>> few days. This commit, 70f3a9ca, and commit a66c275b both cause
>> regression on one of our systems running mass-storage gadget.
>
> I can't see how a66c275b could cause any issues. Our top half runs in
> hardirq context with IRQs disabled; this has been discussed several times.
>
Yes I followed that and I'm also not sure how this can affect
it. I was hoping you might have some idea :)
I'll look into it in more detail later and let you know.
>> a66c275b was introduced first, and until 70f3a9ca is introduced
>> if we revert just that, it works fine. 70f3a9ca causes similar
>> issues. So we must revert both in order to get back to a working
>> state.
>>
>> Failure happens during enumeration and appears to be a race
>> condition in the event handling.
>>
>> Attached are driver logs/traces for the failure with a66c275b.
>
> All I see is a bunch of Start Transfer commands which failed. That's
> odd. Which version of the core are you using ? Dwc3 or dwc31 ?
>
USB 3.0
John
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