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

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

On 08-06-2024 00:57, Thinh Nguyen wrote:
> On Fri, Jun 07, 2024, Mike Looijmans wrote:
>> On 06-06-2024 22:21, Thinh Nguyen wrote:
>>> On Thu, Jun 06, 2024, Mike Looijmans wrote:
>>>> 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?
>>>>
>>> Bit(4) of event info (0003) from device event value (00030601) indicates
>>> usb2 speed.
>>>
>>> Register DSTS field 2:0 indicates fullspeed. Even though this was
>>> captured after disconnection, the linkstate did not change, which led me
>>> to think that the connected speed did not change to Es.Disable either.
>>>
>>>> Do you want me to send new traces?
>>>>
>>> Can you also try to disable usb3 phy suspend with
>>> "snps,dis_u3_susphy_quirk" if you think it's connected in SuperSpeed?
>> Added this to the devicetree, but also no change in behavior.
>>
>>
>>> Please capture the traces again if it's operating in SuperSpeed.
>> I've attached new traces. Connected at superspeed (host reports "superspeed"
>> in its dmesg log, and the real data transfer speed is way above highspeed)
>>
>> I added register dumps before and after the disconnect.
>>
> Thanks for the trace. It's indeed operating in SuperSpeed in the
> connected regdump. However, the GUSB3PIPECTL.SUSPENDENABLE is still set.
> Can you double check if you properly set the "snps,dis_u3_susphy_quirk"?

The trace was made before I added the property. It doesn't change the 
behavior. Should I create a new trace?


-- 
Mike Looijmans
System Expert

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