Re: [PATCH] usb: dwc3: gadget: Fix spurious suspend event during HS link training

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

On Thu, Sep 03, 2026, Saranya R wrote:
> During HS link training, a spurious DWC3_DEVICE_EVENT_SUSPEND carrying
> link state U3 is fired before CONNECT_DONE completes enumeration. At
> this point gadget->speed is USB_SPEED_UNKNOWN since CONNECT_DONE has
> not yet run. Calling dwc3_gadget_suspend_interrupt() here triggers an
> unwanted composite_suspend, causing the charger framework to drop
> current to 2mA and then ramp back to 500mA on every USB connection.
> 
> Fix this by skipping suspend event processing when gadget->speed is
> USB_SPEED_UNKNOWN. This precisely targets the pre-enumeration window
> without affecting genuine suspend events: a real suspend at ADDRESS
> state (required for BC1.2 compliance) only arrives after CONNECT_DONE
> sets gadget->speed to the negotiated speed, so gadget->speed is no
> longer UNKNOWN at that point.
> 
> Fixes: 4decf4060ecf ("usb: dwc3: gadget: Change condition for processing suspend event")

This is a hardware issue. The commit referenced in the Fixes tag is
unrelated. You can add a Cc stable and indicate how far back this should
be backported, but I don't think we should have the fixes tag here.

Thanks,
Thinh

> Signed-off-by: Saranya R <saranya.r@oss.qualcomm.com>
> ---
>  drivers/usb/dwc3/gadget.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index bfb20c3ac392..7d0d24b6c04d 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4465,8 +4465,18 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
>  		break;
>  	case DWC3_DEVICE_EVENT_SUSPEND:
>  		/* It changed to be suspend event for version 2.30a and above */
> -		if (!DWC3_VER_IS_PRIOR(DWC3, 230A))
> -			dwc3_gadget_suspend_interrupt(dwc, event->event_info);
> +		if (!DWC3_VER_IS_PRIOR(DWC3, 230A)) {
> +			/*
> +			 * A spurious U3 suspend event is fired during HS link
> +			 * training before CONNECT_DONE sets the gadget speed.
> +			 * Ignore it at that point to avoid triggering an unwanted
> +			 * composite_suspend. A genuine suspend at ADDRESS state
> +			 * (required for BC1.2 compliance) only arrives after
> +			 * CONNECT_DONE, so gadget->speed is no longer UNKNOWN then.
> +			 */
> +			if (dwc->gadget->speed != USB_SPEED_UNKNOWN)
> +				dwc3_gadget_suspend_interrupt(dwc, event->event_info);
> +		}
>  		break;
>  	case DWC3_DEVICE_EVENT_SOF:
>  	case DWC3_DEVICE_EVENT_ERRATIC_ERROR:
> -- 
> 2.34.1
>