[PATCH v2] usb: dwc3: core: Stop processing of pending events if controller is halted

[Selvarasu Ganesan <selvarasu.g@samsung.com>]

This commit addresses an issue where events were being processed when
the controller was in a halted state. To fix this issue by stop
processing the events as the event count was considered stale or
invalid when the controller was halted.

Fixes: fc8bb91bc83e ("usb: dwc3: implement runtime PM")
Cc: stable <stable@kernel.org>
Signed-off-by: Selvarasu Ganesan <selvarasu.g@samsung.com>
Suggested-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---

Changes in v2:
- Updated the code changes that suggested by reviewer (Thinh Nguyen).
- Link to v1: https://lore.kernel.org/lkml/20240719110100.329-1-selvarasu.g@samsung.com/
---
 drivers/usb/dwc3/core.c   | 22 +++++++++++++++++++---
 drivers/usb/dwc3/core.h   |  4 ----
 drivers/usb/dwc3/gadget.c | 11 -----------
 3 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9eb085f359ce..65ae5203b89e 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -544,6 +544,7 @@ static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned int length)
 int dwc3_event_buffers_setup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
+	u32				reg;
 
 	if (!dwc->ev_buf)
 		return 0;
@@ -556,8 +557,10 @@ int dwc3_event_buffers_setup(struct dwc3 *dwc)
 			upper_32_bits(evt->dma));
 	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0),
 			DWC3_GEVNTSIZ_SIZE(evt->length));
-	dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0);
 
+	/* Clear any stale event */
+	reg = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
+	dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), reg);
 	return 0;
 }
 
@@ -584,7 +587,10 @@ void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
 	dwc3_writel(dwc->regs, DWC3_GEVNTADRHI(0), 0);
 	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), DWC3_GEVNTSIZ_INTMASK
 			| DWC3_GEVNTSIZ_SIZE(0));
-	dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 0);
+
+	/* Clear any stale event */
+	reg = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
+	dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), reg);
 }
 
 static void dwc3_core_num_eps(struct dwc3 *dwc)
@@ -2499,7 +2505,11 @@ static int dwc3_runtime_resume(struct device *dev)
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
-		dwc3_gadget_process_pending_events(dwc);
+		if (dwc->pending_events) {
+			pm_runtime_put(dwc->dev);
+			dwc->pending_events = false;
+			enable_irq(dwc->irq_gadget);
+		}
 		break;
 	case DWC3_GCTL_PRTCAP_HOST:
 	default:
@@ -2589,6 +2599,12 @@ static void dwc3_complete(struct device *dev)
 static const struct dev_pm_ops dwc3_dev_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
 	.complete = dwc3_complete,
+
+	/*
+	 * Runtime suspend halts the controller on disconnection. It replies on
+	 * platforms with custom connection notification to start the controller
+	 * again.
+	 */
 	SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
 			dwc3_runtime_idle)
 };
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index c71240e8f7c7..9c508e0c5cdf 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1675,7 +1675,6 @@ static inline void dwc3_otg_host_init(struct dwc3 *dwc)
 #if !IS_ENABLED(CONFIG_USB_DWC3_HOST)
 int dwc3_gadget_suspend(struct dwc3 *dwc);
 int dwc3_gadget_resume(struct dwc3 *dwc);
-void dwc3_gadget_process_pending_events(struct dwc3 *dwc);
 #else
 static inline int dwc3_gadget_suspend(struct dwc3 *dwc)
 {
@@ -1687,9 +1686,6 @@ static inline int dwc3_gadget_resume(struct dwc3 *dwc)
 	return 0;
 }
 
-static inline void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
-{
-}
 #endif /* !IS_ENABLED(CONFIG_USB_DWC3_HOST) */
 
 #if IS_ENABLED(CONFIG_USB_DWC3_ULPI)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 291bc549935b..10178e5eda5a 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -4728,14 +4728,3 @@ int dwc3_gadget_resume(struct dwc3 *dwc)
 
 	return dwc3_gadget_soft_connect(dwc);
 }
-
-void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
-{
-	if (dwc->pending_events) {
-		dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
-		dwc3_thread_interrupt(dwc->irq_gadget, dwc->ev_buf);
-		pm_runtime_put(dwc->dev);
-		dwc->pending_events = false;
-		enable_irq(dwc->irq_gadget);
-	}
-}
-- 
2.17.1