Bluetooth: btusb: Don't fail external suspend requests

Commit 4e0a1d8b
("Bluetooth: btusb: Don't suspend when there are connections")
introduces a check for connections to prevent auto-suspend but that
actually ignored the fact the .suspend callback can be called for
external suspend requests which
Documentation/driver-api/usb/power-management.rst states the following:

 'External suspend calls should never be allowed to fail in this way,
 only autosuspend calls.  The driver can tell them apart by applying
 the :c:func:`PMSG_IS_AUTO` macro to the message argument to the
 ``suspend`` method; it will return True for internal PM events
 (autosuspend) and False for external PM events.'

In addition to that align system suspend with USB suspend by using
hci_suspend_dev since otherwise the stack would be expecting events
such as advertising reports which may not be delivered while the
transport is suspended.

Fixes: 4e0a1d8b ("Bluetooth: btusb: Don't suspend when there are connections")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Tested-by: Kiran K <kiran.k@intel.com>

drivers/bluetooth/btusb.c

@@ -4038,16 +4038,29 @@ static void btusb_disconnect(struct usb_interface *intf)
 static int btusb_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct btusb_data *data = usb_get_intfdata(intf);
+	int err;
 
 	BT_DBG("intf %p", intf);
 
-	/* Don't suspend if there are connections */
-	if (hci_conn_count(data->hdev))
+	/* Don't auto-suspend if there are connections; external suspend calls
+	 * shall never fail.
+	 */
+	if (PMSG_IS_AUTO(message) && hci_conn_count(data->hdev))
 		return -EBUSY;
 
 	if (data->suspend_count++)
 		return 0;
 
+	/* Notify Host stack to suspend; this has to be done before stopping
+	 * the traffic since the hci_suspend_dev itself may generate some
+	 * traffic.
+	 */
+	err = hci_suspend_dev(data->hdev);
+	if (err) {
+		data->suspend_count--;
+		return err;
+	}
+
 	spin_lock_irq(&data->txlock);
 	if (!(PMSG_IS_AUTO(message) && data->tx_in_flight)) {
 		set_bit(BTUSB_SUSPENDING, &data->flags);
@@ -4055,6 +4068,7 @@ static int btusb_suspend(struct usb_interface *intf, pm_message_t message)
 	} else {
 		spin_unlock_irq(&data->txlock);
 		data->suspend_count--;
+		hci_resume_dev(data->hdev);
 		return -EBUSY;
 	}
 
@@ -4175,6 +4189,8 @@ static int btusb_resume(struct usb_interface *intf)
 	spin_unlock_irq(&data->txlock);
 	schedule_work(&data->work);
 
+	hci_resume_dev(data->hdev);
+
 	return 0;
 
 failed: