if dma transfer fails, retry

embassy-stm32/CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased - ReleaseDate
 
+- fix: ringuffered DMA does retry in write_exact if failed
 - feat: allow granular stop for regular usart
 - feat: Add continuous waveform method to SimplePWM
 - change: remove waveform timer method

embassy-stm32/src/dma/gpdma/ringbuffered.rs

@@ -246,9 +246,18 @@ impl<'a, W: Word> WritableRingBuffer<'a, W> {
 
     /// Write an exact number of elements to the ringbuffer.
     pub async fn write_exact(&mut self, buffer: &[W]) -> Result<usize, Error> {
-        self.ringbuf
+        match self
+            .ringbuf
             .write_exact(&mut DmaCtrlImpl(self.channel.reborrow()), buffer)
             .await
+        {
+            Ok(n) => Ok(n),
+            Err(_) => {
+                self.ringbuf
+                    .write_exact(&mut DmaCtrlImpl(self.channel.reborrow()), buffer)
+                    .await
+            }
+        }
     }
 
     /// Wait for any ring buffer write error.