From f78aa4f936b8bcdd8237f070125e60595f582eb3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Kr=C3=B6ger?= <timokroeger93@gmail.com>
Date: Sat, 1 Apr 2023 14:31:24 +0200
Subject: [PATCH 1/2] rp: Allow zero len reads for buffered uart

Prevents the read methods from getting stuck forever.
---
 embassy-rp/src/uart/buffered.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/embassy-rp/src/uart/buffered.rs b/embassy-rp/src/uart/buffered.rs
index 1a573b31..9aa0b571 100644
--- a/embassy-rp/src/uart/buffered.rs
+++ b/embassy-rp/src/uart/buffered.rs
@@ -175,6 +175,10 @@ impl<'d, T: Instance> BufferedUartRx<'d, T> {
 
     fn read<'a>(buf: &'a mut [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 rx_reader = unsafe { state.rx_buf.reader() };
             let n = rx_reader.pop(|data| {
@@ -202,6 +206,10 @@ impl<'d, T: Instance> BufferedUartRx<'d, T> {
     }
 
     pub fn blocking_read(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        if buf.is_empty() {
+            return Ok(0);
+        }
+
         loop {
             let state = T::state();
             let mut rx_reader = unsafe { state.rx_buf.reader() };

From 7ef6a3cfb22ee1e497fcea37a019ca32d22298b7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Kr=C3=B6ger?= <timokroeger93@gmail.com>
Date: Sun, 2 Apr 2023 14:36:32 +0200
Subject: [PATCH 2/2] rp: Allow zero len writes for buffered uart

Prevents the write methods from getting stuck forever.
---
 embassy-rp/src/uart/buffered.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/embassy-rp/src/uart/buffered.rs b/embassy-rp/src/uart/buffered.rs
index 9aa0b571..c620ed08 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() };