rp: Allow zero len writes for buffered uart

Prevents the write methods from getting stuck forever.

1 files changed, 8 insertions, 0 deletions

diff --git a/embassy-rp/src/uart/buffered.rs b/embassy-rp/src/uart/buffered.rs
index 9aa0b5714..c620ed08c 100644
--- a/embassy-rp/src/uart/buffered.rs
+++ b/embassy-rp/src/uart/buffered.rs
@@ -301,6 +301,10 @@ impl<'d, T: Instance> BufferedUartTx<'d, T> {
 
     fn write<'a>(buf: &'a [u8]) -> impl Future<Output = Result<usize, Error>> + 'a {
         poll_fn(move |cx| {
+            if buf.is_empty() {
+                return Poll::Ready(Ok(0));
+            }
+
             let state = T::state();
             let mut tx_writer = unsafe { state.tx_buf.writer() };
             let n = tx_writer.push(|data| {
@@ -335,6 +339,10 @@ impl<'d, T: Instance> BufferedUartTx<'d, T> {
     }
 
     pub fn blocking_write(&mut self, buf: &[u8]) -> Result<usize, Error> {
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
         loop {
             let state = T::state();
             let mut tx_writer = unsafe { state.tx_buf.writer() };