[on-host] added serialport timeout explicitly

on-host/src/main.rs

@@ -69,6 +69,7 @@ fn main() -> Result<()> {
     };
     debug!("connecting to serial port {}...", port_name);
     let mut port = serialport::new(port_name, args.baud_rate)
+        .timeout(Duration::from_millis(100))
         .open()
         .into_diagnostic()
         .wrap_err("Failed to open serial port")?;