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

[Krishna Kurapati PSSNV]

On 6/4/2024 10:56 AM, 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.

Hi Mike,

 I may be wrong, but can you help understand the mechanism as to how 
disconnect interrupt is generated in your targets. For example, on QC 
SoC's, this happens when HS_PHY_CTRL reg VBUS_VALID bit is cleared and 
cable is disconnected. This is because the vbus line is not routed to 
controller. But from my calls with Synopsys previously, I remember that 
the vbus line is routed to the controller as well for other OEMs. In 
your SoC, what is the indication to controller that vbus is absent ?

Also, after this happens, do you see the next plug in working ?

Regards,
Krishna,