From eea9ecff6541a9632bdcf51d484b9f209028ec61 Mon Sep 17 00:00:00 2001
From: Jan Niehusmann <jan@gondor.com>
Date: Tue, 4 Feb 2025 22:15:59 +0100
Subject: [PATCH] Fix implementations of embedded_io::Write for UartPeripheral
 (#895)

Fixes #840
---
 rp2040-hal/src/uart/peripheral.rs | 5 +++--
 rp2040-hal/src/uart/writer.rs     | 1 +
 rp235x-hal/src/uart/peripheral.rs | 5 +++--
 rp235x-hal/src/uart/writer.rs     | 1 +
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/rp2040-hal/src/uart/peripheral.rs b/rp2040-hal/src/uart/peripheral.rs
index 6435229db..ab856f221 100644
--- a/rp2040-hal/src/uart/peripheral.rs
+++ b/rp2040-hal/src/uart/peripheral.rs
@@ -504,8 +504,9 @@ impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::ReadReady
 
 impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::Write for UartPeripheral<Enabled, D, P> {
     fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
-        self.write_full_blocking(buf);
-        Ok(buf.len())
+        // Blocks if and only if no bytes can be written.
+        let remaining = nb::block!(super::writer::write_raw(&self.device, buf)).unwrap(); // Infallible
+        Ok(buf.len() - remaining.len())
     }
     fn flush(&mut self) -> Result<(), Self::Error> {
         nb::block!(super::writer::transmit_flushed(&self.device)).unwrap(); // Infallible
diff --git a/rp2040-hal/src/uart/writer.rs b/rp2040-hal/src/uart/writer.rs
index 47bc5a0aa..51fa1ecab 100644
--- a/rp2040-hal/src/uart/writer.rs
+++ b/rp2040-hal/src/uart/writer.rs
@@ -214,6 +214,7 @@ impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::ErrorType for Writer<D,
 
 impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::Write for Writer<D, P> {
     fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        // Blocks if and only if no bytes can be written.
         let remaining = nb::block!(write_raw(&self.device, buf)).unwrap(); // Infallible
         Ok(buf.len() - remaining.len())
     }
diff --git a/rp235x-hal/src/uart/peripheral.rs b/rp235x-hal/src/uart/peripheral.rs
index 95421d3b8..064875987 100644
--- a/rp235x-hal/src/uart/peripheral.rs
+++ b/rp235x-hal/src/uart/peripheral.rs
@@ -504,8 +504,9 @@ impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::ReadReady
 
 impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::Write for UartPeripheral<Enabled, D, P> {
     fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
-        self.write_full_blocking(buf);
-        Ok(buf.len())
+        // Blocks if and only if no bytes can be written.
+        let remaining = nb::block!(super::writer::write_raw(&self.device, buf)).unwrap(); // Infallible
+        Ok(buf.len() - remaining.len())
     }
     fn flush(&mut self) -> Result<(), Self::Error> {
         nb::block!(super::writer::transmit_flushed(&self.device)).unwrap(); // Infallible
diff --git a/rp235x-hal/src/uart/writer.rs b/rp235x-hal/src/uart/writer.rs
index ac9c4779c..2f49c2648 100644
--- a/rp235x-hal/src/uart/writer.rs
+++ b/rp235x-hal/src/uart/writer.rs
@@ -215,6 +215,7 @@ impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::ErrorType for Writer<D,
 
 impl<D: UartDevice, P: ValidUartPinout<D>> embedded_io::Write for Writer<D, P> {
     fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        // Blocks if and only if no bytes can be written.
         let remaining = nb::block!(write_raw(&self.device, buf)).unwrap(); // Infallible
         Ok(buf.len() - remaining.len())
     }