Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq

From	Felipe Balbi <balbi@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq
Date	2016-10-13 13:30 +0200
Message-ID	<srMn0-2Ty-17@gated-at.bofh.it> (permalink)
References	(3 earlier) <srJ5L-CJ-11@gated-at.bofh.it> <srJfr-Vf-13@gated-at.bofh.it> <srKXT-1LD-5@gated-at.bofh.it> <srLTX-2pk-1@gated-at.bofh.it> <srMdk-2NV-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

Hi,

Baolin Wang <baolin.wang@linaro.org> writes:
>>> Baolin Wang <baolin.wang@linaro.org> writes:
>>>>>>> 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.
>>>
>>> heh, 100us *is* enough. However we still get an IRQ because we requested
>>> for it. If you want to fix this, then you need to find a way to get rid
>>> of that 100us udelay() and add a proper wait_for_completion() to delay
>>> execution until command complete IRQ fires up.
>>
>> I haven't tested this yet, but it shows the idea (I think we might still
>> have a race with ep_queue if we're still waiting for End Transfer, but
>
> Yes, maybe we need check DWC3_EP_END_TRANSFER_PENDING flag when
> queuing one request.

Yeah, I'll add that check later. I still need to make sure we would
still try to kick any transfers that might have been queued while
waiting for End Transfer Command Complete IRQ.

>> that's easy to sort out by checking for DWC3_EP_END_TRANSFER_PENDING
>> before calling kick_transfer). Could you have a look and, perhaps, run a
>> test?
>
> Sure. I will test it and send out the result tomorrow.

Thank you

-- 
balbi

Thread

[PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-12 13:40 +0200
  Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 09:30 +0200
    Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-13 09:40 +0200
      Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 10:00 +0200
        Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-13 10:10 +0200
          Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 12:00 +0200
            Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 13:00 +0200
              Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-13 13:20 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 13:30 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-13 15:10 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-13 15:40 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-14 09:10 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-14 09:50 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Baolin Wang <baolin.wang@linaro.org> - 2016-10-14 11:20 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-14 12:00 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete  before free irq Alan Stern <stern@rowland.harvard.edu> - 2016-10-14 16:40 +0200
                Re: [PATCH v2] usb: dwc3: gadget: Wait for end transfer complete before free irq Felipe Balbi <balbi@kernel.org> - 2016-10-17 10:20 +0200

csiph-web