Markus Schneider-Pargmann [off-list ref] writes:
...

 
+static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
+{
+	/*
+	 * Map and validate the target Linux suspend state to TISCI LPM.
+	 * Default is to let Device Manager select the low power mode.
+	 */
+	switch (pm_suspend_target_state) {
+	case PM_SUSPEND_MEM:
+		if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED) {
+			/*
+			 * For the DM_MANAGED mode the context is reserved for
+			 * internal use and can be 0
+			 */
+			return ti_sci_cmd_prepare_sleep(&info->handle,
+							TISCI_MSG_VALUE_SLEEP_MODE_DM_MANAGED,
+							0, 0, 0);
+		} else {
+			/* DM Managed is not supported by the firmware. */
+			dev_err(info->dev, "Suspend to memory is not supported by the firmware\n");
+			return -EOPNOTSUPP;
+		}
+		break;
+	default:
+		/*
+		 * Do not fail if we don't have action to take for a
+		 * specific suspend mode.
+		 */
+		return 0;
+	}
+
+	return 0;

Looks like this statement is unreachable, may be generating a warning as well.

+}
+

...