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

[Mike Looijmans]

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://docs.kernel.org/driver-api/usb/dwc3.html#required-information
>
>  From the patch you provided, you only apply the change for the usb
> suspend. But did your device go through system suspend? If that's the
> case, then the dwc3 driver will cause a soft-disconnect. Currently that
> will not prompt a state change. We need the tracepoint to know more
> detail.
>
> Until we have the tracepoints, you can experiment with this test patch.
> If my suspiction is correct, then this may resolve your issue:
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 89fc690fdf34..29dbb889a0e2 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2682,6 +2682,8 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
>           */
>          ret = dwc3_gadget_run_stop(dwc, false);
>   
> +       usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
> +
>          /*
>           * Stop the gadget after controller is halted, so that if needed, the
>           * events to update EP0 state can still occur while the run/stop

I tried the patch above, but it doesn't work. Apparently 
dwc3_gadget_soft_disconnect() doesn't get called when I unplug the cable.

--

Mike Looijmans
System Expert

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