pub async fn wait_for_done(&mut self) {
            if self.dma_result.is_some() {
                return;
            }
            let future = DmaRxFuture::new(&mut self.parl_io.rx_channel);
            self.dma_result = Some(future.await);
        }
Waits for [Self::is_done] to return true.
esp-hal/src/parl_io.rs