Bluetooth: Skip vendor diagnostic configuration for HCI User Channel

index 43fecd59dfef..7655b4005dfb 100644
@@ -148,13 +148,13 @@ static ssize_t vendor_diag_write(struct file *file, const char __user *user_buf,
 		return -EINVAL;
 
 	/* When the diagnostic flags are not persistent and the transport
-	 * is not active, then there is no need for the vendor callback.
-	 *
-	 * Instead just store the desired value. If needed the setting
-	 * will be programmed when the controller gets powered on.
+	 * is not active or in user channel operation, then there is no need
+	 * for the vendor callback. Instead just store the desired value and
+	 * the setting will be programmed when the controller gets powered on.
 	 */
 	if (test_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks) &&
-	    !test_bit(HCI_RUNNING, &hdev->flags))
+	    (!test_bit(HCI_RUNNING, &hdev->flags) ||
+	     hci_dev_test_flag(hdev, HCI_USER_CHANNEL)))
 		goto done;
 
 	hci_req_sync_lock(hdev);

@@ -1419,6 +1419,7 @@ static int hci_dev_do_open(struct hci_dev *hdev)
 	 * completed.
 	 */
 	if (test_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks) &&
+	    !hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
 	    hci_dev_test_flag(hdev, HCI_VENDOR_DIAG) && hdev->set_diag)
 		ret = hdev->set_diag(hdev, true);