Remove unnecessary use of atomic-polyfill.

Only use it when CAS is actually needed.

embassy-stm32/src/adc/v4.rs

@@ -1,4 +1,5 @@
-use atomic_polyfill::{AtomicU8, Ordering};
+use core::sync::atomic::{AtomicU8, Ordering};
+
 use embedded_hal_02::blocking::delay::DelayUs;
 use pac::adc::vals::{Adcaldif, Boost, Difsel, Exten, Pcsel};
 use pac::adccommon::vals::Presc;

embassy-stm32/src/flash/f4.rs

@@ -1,7 +1,6 @@
 use core::convert::TryInto;
 use core::ptr::write_volatile;
-
-use atomic_polyfill::{fence, Ordering};
+use core::sync::atomic::{fence, Ordering};
 
 use super::{ERASE_SIZE, FLASH_BASE, FLASH_SIZE};
 use crate::flash::Error;

embassy-stm32/src/flash/f7.rs

@@ -1,7 +1,6 @@
 use core::convert::TryInto;
 use core::ptr::write_volatile;
-
-use atomic_polyfill::{fence, Ordering};
+use core::sync::atomic::{fence, Ordering};
 
 use crate::flash::Error;
 use crate::pac;

embassy-stm32/src/flash/h7.rs

@@ -41,7 +41,7 @@ pub(crate) unsafe fn blocking_write(offset: u32, buf: &[u8]) -> Result<(), Error
 
     cortex_m::asm::isb();
     cortex_m::asm::dsb();
-    atomic_polyfill::fence(atomic_polyfill::Ordering::SeqCst);
+    core::sync::atomic::fence(core::sync::atomic::Ordering::SeqCst);
 
     let ret = {
         let mut ret: Result<(), Error> = Ok(());
@@ -70,7 +70,7 @@ pub(crate) unsafe fn blocking_write(offset: u32, buf: &[u8]) -> Result<(), Error
 
     cortex_m::asm::isb();
     cortex_m::asm::dsb();
-    atomic_polyfill::fence(atomic_polyfill::Ordering::SeqCst);
+    core::sync::atomic::fence(core::sync::atomic::Ordering::SeqCst);
 
     ret
 }

embassy-stm32/src/i2c/v2.rs

@@ -1,8 +1,8 @@
 use core::cmp;
 use core::future::poll_fn;
+use core::sync::atomic::{AtomicUsize, Ordering};
 use core::task::Poll;
 
-use atomic_polyfill::{AtomicUsize, Ordering};
 use embassy_embedded_hal::SetConfig;
 use embassy_hal_common::drop::OnDrop;
 use embassy_hal_common::{into_ref, PeripheralRef};
@@ -131,7 +131,8 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
 
         if isr.tcr() || isr.tc() {
             let state = T::state();
-            state.chunks_transferred.fetch_add(1, Ordering::Relaxed);
+            let transferred = state.chunks_transferred.load(Ordering::Relaxed);
+            state.chunks_transferred.store(transferred + 1, Ordering::Relaxed);
             state.waker.wake();
         }
         // The flag can only be cleared by writting to nbytes, we won't do that here, so disable

embassy-stm32/src/usart/buffered.rs

@@ -1,8 +1,8 @@
 use core::cell::RefCell;
 use core::future::poll_fn;
+use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::Poll;
 
-use atomic_polyfill::{compiler_fence, Ordering};
 use embassy_cortex_m::peripheral::{PeripheralMutex, PeripheralState, StateStorage};
 use embassy_hal_common::ring_buffer::RingBuffer;
 use embassy_sync::waitqueue::WakerRegistration;

embassy-stm32/src/usart/mod.rs

@@ -2,9 +2,9 @@
 
 use core::future::poll_fn;
 use core::marker::PhantomData;
+use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::Poll;
 
-use atomic_polyfill::{compiler_fence, Ordering};
 use embassy_cortex_m::interrupt::InterruptExt;
 use embassy_futures::select::{select, Either};
 use embassy_hal_common::drop::OnDrop;