On 13 October 2016 at 15:51, Felipe Balbi <ba...@kernel.org> wrote:
> Baolin Wang <baolin.w...@linaro.org> writes:
>> On 13 October 2016 at 15:02, Felipe Balbi <ba...@kernel.org> wrote:
>>> Baolin Wang <baolin.w...@linaro.org> writes:
>>>> @@ -1742,6 +1791,17 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
>>>> dwc->gadget_driver = NULL;
>>>> spin_unlock_irqrestore(&dwc->lock, flags);
>>>> + /*
>>>> + * Since the xHCI will share the same interrupt with gadget, thus
>>>> + * free the gadget irq, it will not shutdown this gadget irq line.
>>>> + * the gadget driver can not handle the end transfer command complete
>>>> + * event after free the gadget irq, which will hang the system to
>>>> + *
>>>> + * So we should wait for the end transfer command complete event
>>>> + * free it to avoid this situation.
>>>> + */
>>>> + dwc3_wait_command_complete(dwc);
>>> this doesn't make sense. We have already masked all interrupts before
>>> getting here. We have also, already, disabled all endpoints.
>> No, you just mask the interrupts described in DEVTEN register, and you
>> did not disable the endpoint command complete event.
> True that
>>> I'm thinking this is a bug in configfs interface of Gadget API, not
>>> dwc3. The only reason for this to happen would be if we get to
>>> ->udc_stop() with endpoints still enabled.
>>> Can you check if that's the case? i.e. can you check if any endpoints
>>> are still enabled when we get here?
>> No, it is not any endpoints are still enabled. Like I said in commit
>> message, we will start end transfer command when disable the endpoint,
>> if the end transfer command complete event comes after we have freed
>> the gadget irq, it will trigger the interrupt line all the time to
>> crash the system.
> I see what the problem is. Databook tells us we *must* set CMDIOC when
> issuing EndTransfer command and we should always wait for Command
> Complete IRQ. However, we took a shortcut and just delayed for 100us
> after issuing End Transfer.
Yes, but 100us delay is not enough in some scenarios, like changing
function with configfs frequently, we will met problems.
> It seems as if *that* should be fixed. We should start actually waiting
> for Command Complete IRQ.
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