From be66e0f7cec742d580a224f12a79b2ab2ca78e37 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Sun, 30 Apr 2023 09:30:10 +0200
Subject: [PATCH] rp/uart: make dma multicore-safe

running rx and tx on different cores could lead to hangs if the dmacr
register modifys run concurrently. this is bad.
---
 embassy-rp/src/uart/mod.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/embassy-rp/src/uart/mod.rs b/embassy-rp/src/uart/mod.rs
index 0b323978..f198afe2 100644
--- a/embassy-rp/src/uart/mod.rs
+++ b/embassy-rp/src/uart/mod.rs
@@ -206,7 +206,7 @@ impl<'d, T: Instance> UartTx<'d, T, Async> {
     pub async fn write(&mut self, buffer: &[u8]) -> Result<(), Error> {
         let ch = self.tx_dma.as_mut().unwrap();
         let transfer = unsafe {
-            T::regs().uartdmacr().modify(|reg| {
+            T::regs().uartdmacr().write_set(|reg| {
                 reg.set_txdmae(true);
             });
             // If we don't assign future to a variable, the data register pointer
@@ -296,7 +296,7 @@ impl<'d, T: Instance> UartRx<'d, T, Async> {
     pub async fn read(&mut self, buffer: &mut [u8]) -> Result<(), Error> {
         let ch = self.rx_dma.as_mut().unwrap();
         let transfer = unsafe {
-            T::regs().uartdmacr().modify(|reg| {
+            T::regs().uartdmacr().write_set(|reg| {
                 reg.set_rxdmae(true);
             });
             // If we don't assign future to a variable, the data register pointer