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

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

On 13-06-2024 02:32, Thinh Nguyen wrote:
> On Tue, Jun 11, 2024, Mike Looijmans wrote:
>> 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"?
>>>
>> I've attached a trace with both "quirks" in the devicetree:
>>      snps,dis_u2_susphy_quirk;
>>      snps,dis_u3_susphy_quirk;
>>
>> Interestingly, it still goes into "suspended" mode when I remove the cable.
>>
> 
> Wait, I thought the host initiated the usb suspend. Did you trigger usb
> suspend by putting the host in suspend? Or does the suspend event only
> come when you perform a disconnect?

All I do is unplug the cable. The host (PC running Ubuntu 22) doesn't eject or 
suspend or anything like that.


> 
> Can you confirm if the suspend event was there before you disconnect the
> device?

Disconnecting the cable is what leads to the "suspend" event.

M.