Bluetooth: hci_sync: Fix suspend performance regression

This attempts to fix suspend performance when there is no connections by
not updating the event mask.

Fixes: ef61b6e ("Bluetooth: Always set event mask on suspend")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/hci_sync.c

@@ -5549,17 +5549,21 @@ int hci_suspend_sync(struct hci_dev *hdev)
 	/* Prevent disconnects from causing scanning to be re-enabled */
 	hci_pause_scan_sync(hdev);
 
-	/* Soft disconnect everything (power off) */
-	err = hci_disconnect_all_sync(hdev, HCI_ERROR_REMOTE_POWER_OFF);
-	if (err) {
-		/* Set state to BT_RUNNING so resume doesn't notify */
-		hdev->suspend_state = BT_RUNNING;
-		hci_resume_sync(hdev);
-		return err;
-	}
+	if (hci_conn_count(hdev)) {
+		/* Soft disconnect everything (power off) */
+		err = hci_disconnect_all_sync(hdev, HCI_ERROR_REMOTE_POWER_OFF);
+		if (err) {
+			/* Set state to BT_RUNNING so resume doesn't notify */
+			hdev->suspend_state = BT_RUNNING;
+			hci_resume_sync(hdev);
+			return err;
+		}
 
-	/* Update event mask so only the allowed event can wakeup the host */
-	hci_set_event_mask_sync(hdev);
+		/* Update event mask so only the allowed event can wakeup the
+		 * host.
+		 */
+		hci_set_event_mask_sync(hdev);
+	}
 
 	/* Only configure accept list if disconnect succeeded and wake
 	 * isn't being prevented.