Re: USB DWC2 stops responding when insert/remove cable multiple times

[Minas Harutyunyan <Minas.Harutyunyan-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>]

Hi Otavio,

On 2/17/2020 4:30 PM, Otavio Salvador wrote:
> Hello Minas,
> 
> On Mon, Feb 17, 2020 at 5:58 AM Minas Harutyunyan
> <Minas.Harutyunyan@synopsys.com> wrote:
>> On 2/14/2020 5:40 PM, Otavio Salvador wrote:
> ...
>>>       [  312.967867] g_serial gadget: high-speed config #2: CDC ACM config
>>>       [  314.828173] dwc2 30180000.usb: new device is high-speed
>>>       [  314.866943] dwc2 30180000.usb: new address 16
>>>       [  314.889550] g_serial gadget: high-speed config #2: CDC ACM config
>>>
>>
>> I assume here you few time disconnected and then connected cable and
>> after last connection even when g_serial seen in last line it stop work.
>> Correct?
> 
> Yes. It stops responding.
> 
>>> The "[  314.889550] g_serial gadget: high-speed config #2: CDC ACM
>>> config" message is the last time it is detected. As mentioned, to
>>> restore the port to work, we need to reload the g_serial module.
>>>
>>> When we reload it, following exception happens:
>>>
>>
>> Actually exception happen in g_serial not dwc2. Why you assume that it
>> because of dwc2?
> 
> Indeed. After reporting this, it does sounds it is two decouple
> issues. The tty seems to be not properly cleaned up and it seems to
> have a resource not properly cleaned up.
> 
Enable debug prints to get full dwc2 debug prints to see what happen 
with dwc2.

> ...
>>> So, I am a bit lost how to debug this so I'd like to know what kind of
>>> information might be useful to find the root cause of it?
>>
>> And despite of above exception, g_serial enumerated it works fine?
> 
> If reloaded the USB is detected but tty seems to not work. It seems it
> fails to free the ttyGS0 previously used and thus it cannot properly
> create the new device.
> 
>> Please provide me dump of follow dwc2 debugfs's: regdump, hw_params, params.
> 
> Do you want this on working and failing state or just the failing one?
> 
After failing.


Thanks,
Minas