Re: BUG with linux 5.9.0 with dwc3 in gadget mode

From: Felipe Balbi <balbi@kernel.org>
To: Ferry Toth <fntoth@gmail.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Jack Pham <jackp@codeaurora.org>
Subject: Re: BUG with linux 5.9.0 with dwc3 in gadget mode
Date: Fri, 06 Nov 2020 16:15:59 +0200	[thread overview]
Message-ID: <87blgar2ow.fsf@kernel.org> (raw)
In-Reply-To: <326aa23e-fabd-f3d6-4778-d036858413a2@gmail.com>

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Hi,

Ferry Toth <fntoth@gmail.com> writes:
>>>> Ferry Toth <fntoth@gmail.com> writes:
>>>>> Op 27-10-2020 om 22:16 schreef Andy Shevchenko:
>>>>>> On Tue, Oct 27, 2020 at 10:13 PM Ferry Toth <fntoth@gmail.com> wrote:
>>>>>>> Op 22-10-2020 om 15:43 schreef Andy Shevchenko:
>>>>>>>> On Thu, Oct 22, 2020 at 4:21 PM Thinh Nguyen <Thinh.Nguyen@synopsys.com> wrote:
>>>>>>>>> Ferry Toth wrote:
>>>>>> ...
>>>>>>
>>>>>>>>> There are some fixes to dwc3 in kernel mainline. Is it possible to test
>>>>>>>>> this against linux-next?
>>>>>>>> I think the best is to wait for v5.10-rc1 and retest.
>>>>>> Can you give a try of v5.10-rc1?
>>>>> Yes, I just tried:
>>>>>
>>>>> I booted in host mode, then flip the switch. Gadget come up, go down
>>>>> once, then come up again and stay up.
>>>> please collect trace events. It's important to figure out why it's going
>>>> down, even if only once. Make sure to collect trace *and* dmesg so we
>>>> can correlate trace with the reenumeration that should show up in dmesg.
>>>>
>>>> thanks
>>> Sorry, I had to replace mobo. Now back on this.
>>>
>>> As is, on Edison I can record with something like "perf record -e
>>> 'dwc3:dwc3_gadget*' -e 'gadget:*' -g -a".
>>> Then get the trace buffer with "perf script > gadget.txt". Then at each
>>> trace point we get a stack trace like:
>>>
>>> file-storage   831 [001]  4445.240038: dwc3:dwc3_gadget_ep_cmd: [FAILED
>>> TO PARSE] name=ep4in cmd=524295 param0=0 param1=0 param2=0 cmd_status=0
>>>       ffffffff9a35b7e7 __traceiter_dwc3_gadget_ep_cmd+0x37
>>> ([kernel.kallsyms])
>>>       ffffffff9a35b7e7 __traceiter_dwc3_gadget_ep_cmd+0x37
>>> ([kernel.kallsyms])
>>>       ffffffff9a35fa40 dwc3_send_gadget_ep_cmd+0x320 ([kernel.kallsyms])
>>>       ffffffff9a3606d0 __dwc3_gadget_kick_transfer+0x200 ([kernel.kallsyms])
>>>       ffffffff9a361114 dwc3_gadget_ep_queue+0xe4 ([kernel.kallsyms])
>>>       ffffffff9a3afc3a usb_ep_queue+0x2a ([kernel.kallsyms])
>>>       ffffffffc047c301 start_transfer.isra.0+0x21 ([kernel.kallsyms])
>>>       ffffffffc047c88a start_in_transfer.isra.0+0x3a ([kernel.kallsyms])
>>>       ffffffffc047c93d send_status+0x8d ([kernel.kallsyms])
>>>       ffffffffc047dd05 fsg_main_thread+0x3c5 ([kernel.kallsyms])
>>>       ffffffff99c853b9 kthread+0xf9 ([kernel.kallsyms])
>>>       ffffffff99c01a32 ret_from_fork+0x22 ([kernel.kallsyms])
>>>
>>> "perf list" shows the tracepoint events, the same as under
>>> /sys/kernel/debug/tracing/events/
>>>
>>> Question is which points to trace (above command fills buffer to 35MB in
>>> 10sec). Do you have suggestions?
>> don't enable any gadget event. Only dwc3 events. Also, enable *all* dwc3
>> events. Usually, I avoid perf when doing this and just go straight to
>> /sys/kernel/trace/.
> Ok, I can do that. But I'm not sure how I turn on tracing and capture 
> the results.

Got you covered ;-)

https://www.kernel.org/doc/html/latest/driver-api/usb/dwc3.html#reporting-bugs


-- 
balbi

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