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

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

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?

Please capture the traces again if it's operating in SuperSpeed.

Thanks,
Thinh