Re: [PATCH v2] usb: dwc3: qcom: Defer VBUS override update during system suspend

[Thinh Nguyen]

Hi,

On Wed, Nov 04, 2026, Prashanth K wrote:
> 
> 
> On 11/4/2026 8:07 AM, Thinh Nguyen wrote:
> > On Fri, Oct 23, 2026, Vladyslav Tymoshchuk wrote:
> >> dwc3_qcom_set_role_notifier() updates the VBUS override in QSCRATCH
> >> synchronously, from the context of the usb_role_switch_set_role()
> >> caller. The glue assumes that role switches only happen from a
> >> freezable workqueue, but that holds for the dwc3 core's mode switch,
> >> not for this notifier: the UCSI connector work, for one, runs on the
> >> non-freezable system workqueue.
> >>
> > 
> > ....
> > 
> > Good catch. However, this should be fixed in the dwc3 core. The
> > pre_set_role notifier can be called from the freezable __dwc3_set_mode()
> > work instead of from the role switch caller. Then glue drivers won't be
> > notified while suspended. This is simpler and applies to all glue
> > drivers.
> 
> I think the problem with that is, dwc3_set_mode doesn't know USB_ROLE
> (especially NONE mode).
> It only knows the mode which is gadget/host/otg. Thats why vendor hooks
> are used in drd.c instead. Perhaps we can cache USB_ROLE into dwc3
> struct and use it later on __dwc3_set_mode.
> 

Yes, the role needs to be cached. Something like the change below.

Hi Vladyslav,

Could you test this change instead to see if it resolves the issue?

Thanks,
Thinh

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index fd5c2cd36c59..99a39c828543 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -169,15 +169,23 @@ static void __dwc3_set_mode(struct work_struct *work)
 	int ret;
 	u32 reg;
 	u32 desired_dr_role;
+	enum usb_role requested_role;
+	bool notify_glue;
 	int i;
 
 	mutex_lock(&dwc->mutex);
 	spin_lock_irqsave(&dwc->lock, flags);
 	desired_dr_role = dwc->desired_dr_role;
+	requested_role = dwc->requested_role;
+	notify_glue = dwc->requested_role_pending;
+	dwc->requested_role_pending = false;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	pm_runtime_get_sync(dwc->dev);
 
+	if (notify_glue)
+		dwc3_pre_set_role(dwc, requested_role);
+
 	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG)
 		dwc3_otg_update(dwc, 0);
 
@@ -287,7 +295,8 @@ static void __dwc3_set_mode(struct work_struct *work)
 	mutex_unlock(&dwc->mutex);
 }
 
-void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
+static void __dwc3_queue_mode(struct dwc3 *dwc, u32 mode, enum usb_role role,
+			      bool notify_glue)
 {
 	unsigned long flags;
 
@@ -296,11 +305,25 @@ void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	dwc->desired_dr_role = mode;
+	if (notify_glue) {
+		dwc->requested_role = role;
+		dwc->requested_role_pending = true;
+	}
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	queue_work(system_freezable_wq, &dwc->drd_work);
 }
 
+void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
+{
+	__dwc3_queue_mode(dwc, mode, USB_ROLE_NONE, false);
+}
+
+void dwc3_set_role(struct dwc3 *dwc, u32 mode, enum usb_role role)
+{
+	__dwc3_queue_mode(dwc, mode, role, true);
+}
+
 u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type)
 {
 	struct dwc3		*dwc = dep->dwc;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index f3dabb37f806..0fbc1a446ae1 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1058,6 +1058,8 @@ struct dwc3_glue_ops {
  * @dr_mode: requested mode of operation
  * @current_dr_role: current role of operation when in dual-role mode
  * @desired_dr_role: desired role of operation when in dual-role mode
+ * @requested_role: role requested
+ * @requested_role_pending: @requested_role is yet to be passed to the glue
  * @edev: extcon handle
  * @edev_nb: extcon notifier
  * @hsphy_mode: UTMI phy mode, one of following:
@@ -1261,6 +1263,8 @@ struct dwc3 {
 	enum usb_dr_mode	dr_mode;
 	u32			current_dr_role;
 	u32			desired_dr_role;
+	enum usb_role		requested_role;
+	bool			requested_role_pending;
 	struct extcon_dev	*edev;
 	struct notifier_block	edev_nb;
 	enum usb_phy_interface	hsphy_mode;
@@ -1614,6 +1618,7 @@ struct dwc3_gadget_ep_cmd_params {
 /* prototypes */
 void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode, bool ignore_susphy);
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode);
+void dwc3_set_role(struct dwc3 *dwc, u32 mode, enum usb_role role);
 u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type);
 
 #define DWC3_IP_IS(_ip)							\
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index f3e37d383627..55036466ec7a 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -439,8 +439,7 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
 	enum usb_role role = mode == DWC3_GCTL_PRTCAP_HOST ?
 				     USB_ROLE_HOST : USB_ROLE_DEVICE;
 
-	dwc3_pre_set_role(dwc, role);
-	dwc3_set_mode(dwc, mode);
+	dwc3_set_role(dwc, mode, role);
 
 	return NOTIFY_DONE;
 }
@@ -468,8 +467,7 @@ static int dwc3_usb_role_switch_set(struct usb_role_switch *sw,
 		break;
 	}
 
-	dwc3_pre_set_role(dwc, role);
-	dwc3_set_mode(dwc, mode);
+	dwc3_set_role(dwc, mode, role);
 	return 0;
 }