Re: [PATCH] usb: dwc3: gadget: Inform system of suspended state

[Mike Looijmans <mike.looijmans@topic.nl>]

On 06-06-2024 02:28, Thinh Nguyen wrote:
> On Wed, Jun 05, 2024, Mike Looijmans wrote:
>> On 05-06-2024 01:06, Thinh Nguyen wrote:
>>> Hi,
>>>
>>> On Tue, Jun 04, 2024, Mike Looijmans wrote:
>>>> On 04-06-2024 03:03, Thinh Nguyen wrote:
>>>>> Hi,
>>>>>
>>>>> On Mon, Jun 03, 2024, Mike Looijmans wrote:
>>>>>> When disconnecting the USB cable on an LS1028 device, nothing happens
>>>>>> in userspace, which keeps thinking everything is still up and running.
>>>>>> Turns out that the DWC3 controller only sends DWC3_DEVICE_EVENT_SUSPEND
>>>>>> in that case, and not a DWC3_DEVICE_EVENT_DISCONNECT as one would
>>>>>> expect. As a result, sysfs attribute "state" remains "configured"
>>>>>> until something resets it.
>>>>>>
>>>>>> Forward the "suspended" state to sysfs, so that the "state" at least
>>>>>> changes into "suspended" when one removes the cable, and hence also
>>>>>> matches the gadget's state when really suspended.
>>>>> On disconnection, did you see disconnect interrupt? If so, it should
>>>>> transition to USB_STATE_NOATTACHED. This change doesn't seem to directly
>>>>> address your issue. Can you provide the driver tracepoints?
>>>> The device doesn't issue a disconnect event, I didn't have tracing enabled
>>>> in the kernel but added some dev_info() calls to determine what was going
>>>> on. Added this to dwc3_process_event_entry():
>>>>
>>>> dev_info(dwc->dev, "event: 0x%x type=0x%x", event->raw, event->type.type);
>>>>
>>>> When disconnecting the cable from the host, I see this:
>>>>
>>>> [   50.841411] dwc3 3110000.usb: event: 0x6084 type=0x42
>>>> [   50.841457] dwc3 3110000.usb: event: 0x4086 type=0x43
>>>> [   50.841494] dwc3 3110000.usb: event: 0x6084 type=0x42
>>>> [   50.841534] dwc3 3110000.usb: event: 0x4086 type=0x43
>>>> [   50.841571] dwc3 3110000.usb: event: 0x4086 type=0x43
>>>> [   52.650990] dwc3 3110000.usb: event: 0x30601 type=0x0
>>>>
>>>> The "0x4086" and "0x6084" messages are endpoint events that occur all the
>>>> time while connected. The last event is the "suspend" one. After that, total
>>>> silence.
>>>>
>>>> If you need traces, please point me to a description on how to obtain them.
>>>>
>>>>
>>> Let me know if you run into issues following this instructions to
>>> capture the tracepoints:
>>> https://urldefense.com/v3/__https://docs.kernel.org/driver-api/usb/dwc3.html*required-information__;Iw!!A4F2R9G_pg!bahfjil5HEUq-fOHAwDfusutLJCLognfyLHTFLiSlVuZotpr99XBGg7nB0zRRnNF_M1pqEKcVa4KxNJwh3_F2dZWwVKTkUY$
>> I've attached the traces as a tarball. Hope it survives.
> Got them. Thanks.
>
>> At the start, the USB is up and running (and doing ethernet+mass storage). I
>> saved the trace after pulling the USB cable.
>>
>  From the capture, we can see that there's no system suspend, so there's
> no soft-disconnect.
>
> Base on the suspend event, you're running in usb2 speed (ignore the
> incorrect U3 state, should be L2):
>
> 	irq/94-dwc3-631     [000] D..1.   149.139290: dwc3_event: event (00030601): Suspend [U3]
>
> The DSTS from the regdump indicated that you're still in L2 despite
> disconnected. Looks like the phy was unable to detect and wakeup from
> the disconnection to notify the controller.
>
> Can you experiment with setting "snps,dis_u2_susphy_quirk" to disable
> usb2 phy suspend.

Adding snps,dis_u2_susphy_quirk doesn't make a difference, behavior is 
identical.


>
> Does your device support SuperSpeed? If so, do you observe the same
> behavior while operating in SuperSpeed?

Just checked, still connects with superspeed. What led you to think it 
was only high speed?

Do you want me to send new traces?



-- 
Mike Looijmans
System Expert

TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl