4 files changed, 24 insertions, 2 deletions

diff --git a/tests/rp/.cargo/config.toml b/tests/rp/.cargo/config.toml
index de7bb0e56..4337924cc 100644
--- a/tests/rp/.cargo/config.toml
+++ b/tests/rp/.cargo/config.toml
@@ -11,7 +11,6 @@ runner = "teleprobe client run"
 rustflags = [
   # Code-size optimizations.
   #"-Z", "trap-unreachable=no",
-  "-C", "inline-threshold=5",
   "-C", "no-vectorize-loops",
 ]
 
diff --git a/tests/stm32/.cargo/config.toml b/tests/stm32/.cargo/config.toml
index 8752da59b..d94342598 100644
--- a/tests/stm32/.cargo/config.toml
+++ b/tests/stm32/.cargo/config.toml
@@ -9,7 +9,6 @@ runner = "teleprobe client run"
 rustflags = [
   # Code-size optimizations.
   #"-Z", "trap-unreachable=no",
-  "-C", "inline-threshold=5",
   "-C", "no-vectorize-loops",
 ]
 
diff --git a/tests/stm32/src/bin/usart.rs b/tests/stm32/src/bin/usart.rs
index 53da30fff..2f601ad0e 100644
--- a/tests/stm32/src/bin/usart.rs
+++ b/tests/stm32/src/bin/usart.rs
@@ -33,6 +33,13 @@ async fn main(_spawner: Spawner) {
         let mut buf = [0; 2];
         usart.blocking_read(&mut buf).unwrap();
         assert_eq!(buf, data);
+
+        // Test flush doesn't hang.
+        usart.blocking_write(&data).unwrap();
+        usart.blocking_flush().unwrap();
+
+        // Test flush doesn't hang if there's nothing to flush
+        usart.blocking_flush().unwrap();
     }
 
     // Test error handling with with an overflow error
diff --git a/tests/stm32/src/bin/usart_dma.rs b/tests/stm32/src/bin/usart_dma.rs
index 266b81809..a34498376 100644
--- a/tests/stm32/src/bin/usart_dma.rs
+++ b/tests/stm32/src/bin/usart_dma.rs
@@ -51,6 +51,23 @@ async fn main(_spawner: Spawner) {
         assert_eq!(tx_buf, rx_buf);
     }
 
+    // Test flush doesn't hang. Check multiple combinations of async+blocking.
+    tx.write(&tx_buf).await.unwrap();
+    tx.flush().await.unwrap();
+    tx.flush().await.unwrap();
+
+    tx.write(&tx_buf).await.unwrap();
+    tx.blocking_flush().unwrap();
+    tx.flush().await.unwrap();
+
+    tx.blocking_write(&tx_buf).unwrap();
+    tx.blocking_flush().unwrap();
+    tx.flush().await.unwrap();
+
+    tx.blocking_write(&tx_buf).unwrap();
+    tx.flush().await.unwrap();
+    tx.blocking_flush().unwrap();
+
     info!("Test OK");
     cortex_m::asm::bkpt();
 }