[PATCH v2] usb: dwc3: gadget: Fix spurious suspend event during HS link training

[PATCH v2] usb: dwc3: gadget: Fix spurious suspend event during HS link training

[Saranya R]

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.

Signed-off-by: Saranya R <saranya.r@oss.qualcomm.com>
---

v2: remove Fixes tag and add cc stable
This issue observed on 6.12 kernel.

---
 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 fa944856f956..a3a59d9d92ef 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4540,8 +4540,18 @@ 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

Re: [PATCH v2] usb: dwc3: gadget: Fix spurious suspend event during HS link training

[Thinh Nguyen]

On Mon, Sep 07, 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.
> 
> Signed-off-by: Saranya R <saranya.r@oss.qualcomm.com>
> ---
> 
> v2: remove Fixes tag and add cc stable
> This issue observed on 6.12 kernel.
> 
> ---
>  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 fa944856f956..a3a59d9d92ef 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4540,8 +4540,18 @@ 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
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

Thanks,
Thinh