From 990dd5e5db7134193259fcf350c0928b9a64df97 Mon Sep 17 00:00:00 2001
From: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Date: Mon, 19 Jun 2023 22:38:27 +0200
Subject: [PATCH 1/2] tests/stm32: do multiple transfers to catch more bugs.

---
 tests/stm32/src/bin/usart_dma.rs | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/tests/stm32/src/bin/usart_dma.rs b/tests/stm32/src/bin/usart_dma.rs
index 50dd2893..c34d9574 100644
--- a/tests/stm32/src/bin/usart_dma.rs
+++ b/tests/stm32/src/bin/usart_dma.rs
@@ -69,24 +69,27 @@ async fn main(_spawner: Spawner) {
     const LEN: usize = 128;
     let mut tx_buf = [0; LEN];
     let mut rx_buf = [0; LEN];
-    for i in 0..LEN {
-        tx_buf[i] = i as u8;
-    }
 
     let (mut tx, mut rx) = usart.split();
 
-    let tx_fut = async {
-        tx.write(&tx_buf).await.unwrap();
-    };
-    let rx_fut = async {
-        rx.read(&mut rx_buf).await.unwrap();
-    };
+    for n in 0..42 {
+        for i in 0..LEN {
+            tx_buf[i] = (i ^ n) as u8;
+        }
 
-    // note: rx needs to be polled first, to workaround this bug:
-    // https://github.com/embassy-rs/embassy/issues/1426
-    join(rx_fut, tx_fut).await;
+        let tx_fut = async {
+            tx.write(&tx_buf).await.unwrap();
+        };
+        let rx_fut = async {
+            rx.read(&mut rx_buf).await.unwrap();
+        };
 
-    assert_eq!(tx_buf, rx_buf);
+        // note: rx needs to be polled first, to workaround this bug:
+        // https://github.com/embassy-rs/embassy/issues/1426
+        join(rx_fut, tx_fut).await;
+
+        assert_eq!(tx_buf, rx_buf);
+    }
 
     info!("Test OK");
     cortex_m::asm::bkpt();

From 428a4ba3f98d81de28f8f72115ed6eff5401b46a Mon Sep 17 00:00:00 2001
From: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Date: Mon, 19 Jun 2023 22:39:08 +0200
Subject: [PATCH 2/2] stm32/gpdma: clear all interrupts after reset.

Reset doesn't clear them, this causes subsequent transfers to instantly
complete because the TC flag was set from before.
---
 embassy-stm32/src/dma/gpdma.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/embassy-stm32/src/dma/gpdma.rs b/embassy-stm32/src/dma/gpdma.rs
index c600df92..b7bcf779 100644
--- a/embassy-stm32/src/dma/gpdma.rs
+++ b/embassy-stm32/src/dma/gpdma.rs
@@ -252,6 +252,7 @@ impl<'a, C: Channel> Transfer<'a, C> {
         super::dmamux::configure_dmamux(&mut *this.channel, request);
 
         ch.cr().write(|w| w.set_reset(true));
+        ch.fcr().write(|w| w.0 = 0xFFFF_FFFF); // clear all irqs
         ch.llr().write(|_| {}); // no linked list
         ch.tr1().write(|w| {
             w.set_sdw(data_size.into());