Re: [RESEND PATCH v3 1/2] usb: dwc3: gadget: Add disconnect checking when changing function dynamically

From: Felipe Balbi
Date: Thu Oct 13 2016 - 08:18:54 EST


Baolin Wang <> writes:
>>>>>>>>>>>> @@ -241,6 +241,9 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned cmd,
>>>>>>>>>>>> int susphy = false;
>>>>>>>>>>>> int ret = -EINVAL;
>>>>>>>>>>>> + if (!dwc->pullups_connected)
>>>>>>>>>>>> + return -ESHUTDOWN;
>>>>>>>>>>>> +
>>>>>>>>> you skip trace_dwc3_gadget_ep_cmd()
>>>>>>>> Yes, we did not need trace here since we did not send out the command.
>>>>>>> What in such case: enumeration will not work and this will be because
>>>>>>> this ESHUTDOWN or wrong pullups_connected usage. Without a trace you
>>>>>>> will not know where the problem is.
>>>>>>> In my opinion this trace could be useful.
>>>>>> We have returned the '-ESHUTDOWN' error number for user to know what
>>>>>> happened.
>>>>> No, this is actually not good and Janusz has a very valid point
>>>>> here. When we're debugging something in dwc3, we want to rely on
>>>>> tracepoints to tell us what's going on. I don't want to have to add more
>>>>> debugging messages to print out that ESHUTDOWN error just so I can
>>>>> figure out what's going on. You should be patching this in a way that
>>>>> the tracepoint is still printed out properly.
>>>> Fine. Will fix this in next version.
>>> BTW, did you test this patch with device mode?
>>> Seems in my setup this fail - DWC3_DEPCMD_SETEPCONFIG for ep0out and
>>> gadget_start() failed (enumeration fail).
>>> Don't we need to queue ep0 cmds before pullup?
>> Baolin, it's clear to me that you're not testing any of the patches
> I am sure I tested every patch I send to you. But this one is really
> my mistake and I thought this is just one small change with just eye
> review. I am really sorry for troubles.

fair enough, luckily Janusz caught it before any harm could be
done. Thanks for taking the time to explain.


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