Hi Felipe, On 13 October 2016 at 19:23, Felipe Balbi <balbi@xxxxxxxxxx> wrote: > > Hi, > > Baolin Wang <baolin.wang@xxxxxxxxxx> writes: >>>> Baolin Wang <baolin.wang@xxxxxxxxxx> 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. OK. But I still worried if there are other races in some places which is not easy to find out by testing. No introducing race condition would be one better solution, anyway I would like to test the patch you send out firstly. > >>> 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 -- Baolin.wang Best Regards -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
