usb: dwc2: host: Fix missing device insertions

If you've got your interrupt signals bouncing a bit as you insert your
USB device, you might end up in a state when the device is connected but
the driver doesn't know it.

Specifically, the observed order is:
 1. hardware sees connect
 2. hardware sees disconnect
 3. hardware sees connect
 4. dwc2_port_intr() - clears connect interrupt
 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()

Now you'll be stuck with the cable plugged in and no further interrupts
coming in but the driver will think we're disconnected.

We'll fix this by checking for the missing connect interrupt and
re-connecting after the disconnect is posted.  We don't skip the
disconnect because if there is a transitory disconnect we really want to
de-enumerate and re-enumerate.

Notes:
1. As part of this change we add a "force" parameter to
   dwc2_hcd_disconnect() so that when we're unloading the module we
   avoid the new behavior.  The need for this was pointed out by John
   Youn.
2. The bit of code needed at the end of dwc2_hcd_disconnect() is
   exactly the same bit of code from dwc2_port_intr().  To avoid
   duplication, we refactor that code out into a new function
   dwc2_hcd_connect().

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/core.h

@@ -1180,12 +1180,14 @@ static inline int dwc2_hsotg_set_test_mode(struct dwc2_hsotg *hsotg,
 
 #if IS_ENABLED(CONFIG_USB_DWC2_HOST) || IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
 extern int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg);
-extern void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg);
+extern void dwc2_hcd_connect(struct dwc2_hsotg *hsotg);
+extern void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force);
 extern void dwc2_hcd_start(struct dwc2_hsotg *hsotg);
 #else
 static inline int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg)
 { return 0; }
-static inline void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_hcd_connect(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force) {}
 static inline void dwc2_hcd_start(struct dwc2_hsotg *hsotg) {}
 static inline void dwc2_hcd_remove(struct dwc2_hsotg *hsotg) {}
 static inline int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq)

drivers/usb/dwc2/core_intr.c

@@ -239,7 +239,7 @@ static void dwc2_handle_otg_intr(struct dwc2_hsotg *hsotg)
 			dev_dbg(hsotg->dev, "a_suspend->a_peripheral (%d)\n",
 				hsotg->op_state);
 			spin_unlock(&hsotg->lock);
-			dwc2_hcd_disconnect(hsotg);
+			dwc2_hcd_disconnect(hsotg, false);
 			spin_lock(&hsotg->lock);
 			hsotg->op_state = OTG_STATE_A_PERIPHERAL;
 		} else {
@@ -401,7 +401,7 @@ static void dwc2_handle_disconnect_intr(struct dwc2_hsotg *hsotg)
 		dwc2_op_state_str(hsotg));
 
 	if (hsotg->op_state == OTG_STATE_A_HOST)
-		dwc2_hcd_disconnect(hsotg);
+		dwc2_hcd_disconnect(hsotg, false);
 
 	dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
 }

drivers/usb/dwc2/hcd.c

@@ -267,16 +267,34 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
 	}
 }
 
+/**
+ * dwc2_hcd_connect() - Handles connect of the HCD
+ *
+ * @hsotg: Pointer to struct dwc2_hsotg
+ *
+ * Must be called with interrupt disabled and spinlock held
+ */
+void dwc2_hcd_connect(struct dwc2_hsotg *hsotg)
+{
+	if (hsotg->lx_state != DWC2_L0)
+		usb_hcd_resume_root_hub(hsotg->priv);
+
+	hsotg->flags.b.port_connect_status_change = 1;
+	hsotg->flags.b.port_connect_status = 1;
+}
+
 /**
  * dwc2_hcd_disconnect() - Handles disconnect of the HCD
  *
  * @hsotg: Pointer to struct dwc2_hsotg
+ * @force: If true, we won't try to reconnect even if we see device connected.
  *
  * Must be called with interrupt disabled and spinlock held
  */
-void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
+void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force)
 {
 	u32 intr;
+	u32 hprt0;
 
 	/* Set status flags for the hub driver */
 	hsotg->flags.b.port_connect_status_change = 1;
@@ -315,6 +333,24 @@ void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
 		dwc2_hcd_cleanup_channels(hsotg);
 
 	dwc2_host_disconnect(hsotg);
+
+	/*
+	 * Add an extra check here to see if we're actually connected but
+	 * we don't have a detection interrupt pending.  This can happen if:
+	 *   1. hardware sees connect
+	 *   2. hardware sees disconnect
+	 *   3. hardware sees connect
+	 *   4. dwc2_port_intr() - clears connect interrupt
+	 *   5. dwc2_handle_common_intr() - calls here
+	 *
+	 * Without the extra check here we will end calling disconnect
+	 * and won't get any future interrupts to handle the connect.
+	 */
+	if (!force) {
+		hprt0 = dwc2_readl(hsotg->regs + HPRT0);
+		if (!(hprt0 & HPRT0_CONNDET) && (hprt0 & HPRT0_CONNSTS))
+			dwc2_hcd_connect(hsotg);
+	}
 }
 
 /**
@@ -2390,7 +2426,7 @@ static void _dwc2_hcd_stop(struct usb_hcd *hcd)
 
 	spin_lock_irqsave(&hsotg->lock, flags);
 	/* Ensure hcd is disconnected */
-	dwc2_hcd_disconnect(hsotg);
+	dwc2_hcd_disconnect(hsotg, true);
 	dwc2_hcd_stop(hsotg);
 	hsotg->lx_state = DWC2_L3;
 	hcd->state = HC_STATE_HALT;

drivers/usb/dwc2/hcd_intr.c

@@ -350,11 +350,7 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
 		dev_vdbg(hsotg->dev,
 			 "--Port Interrupt HPRT0=0x%08x Port Connect Detected--\n",
 			 hprt0);
-		if (hsotg->lx_state != DWC2_L0)
-			usb_hcd_resume_root_hub(hsotg->priv);
-
-		hsotg->flags.b.port_connect_status_change = 1;
-		hsotg->flags.b.port_connect_status = 1;
+		dwc2_hcd_connect(hsotg);
 		hprt0_modify |= HPRT0_CONNDET;
 
 		/*