From 9f28c7ab8d96d19a010246318dee1de73b3ed4ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Kr=C3=B6ger?= <timokroeger93@gmail.com>
Date: Sat, 2 Jan 2021 22:40:36 +0100
Subject: [PATCH] uarte: Do not spin when stopping a receive future

Spinning on drop() is still required when the future has not been
stopped so that DMA finishes before the buffer is released.
---
 embassy-nrf/src/uarte.rs | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/embassy-nrf/src/uarte.rs b/embassy-nrf/src/uarte.rs
index 648298b8..494b92df 100644
--- a/embassy-nrf/src/uarte.rs
+++ b/embassy-nrf/src/uarte.rs
@@ -313,7 +313,7 @@ where
 {
     fn drop(self: &mut Self) {
         if self.uarte.rx_started() {
-            trace!("stoprx");
+            trace!("stoprx (drop)");
 
             self.uarte.instance.events_rxstarted.reset();
             self.uarte
@@ -364,9 +364,20 @@ where
     T: Instance,
 {
     /// Stops the ongoing reception and returns the number of bytes received.
-    pub async fn stop(self) -> usize {
-        drop(self);
-        let len = T::state().rx_done.wait().await;
+    pub async fn stop(mut self) -> usize {
+        let len = if self.uarte.rx_started() {
+            trace!("stoprx (stop)");
+
+            self.uarte.instance.events_rxstarted.reset();
+            self.uarte
+                .instance
+                .tasks_stoprx
+                .write(|w| unsafe { w.bits(1) });
+            T::state().rx_done.wait().await
+        } else {
+            // Transfer was stopped before it even started. No bytes were sent.
+            0
+        };
         len as _
     }
 }