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

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

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!epxtPmXHiizMg5_5igEYiKU483OZb1zcYK1M3afqXxIfgsw_cU_kdz9Rlpf1w-30JF0v4UUkxBViJtx4Prv3ZWchjKNHkKE$
> > 
> >  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.
> 

Thanks for testing. There's no system suspend, so that's expected.

BR,
Thinh