Add memory barriers to H7 flash driver to mitigate PGSERR errors

The stm32h7xx-hal uses only the ordering barrier, while the CubeMX uses the DSB and ISB instructions, to be on the safe side, both are used here.

1 files changed, 8 insertions, 0 deletions

diff --git a/embassy-stm32/src/flash/h7.rs b/embassy-stm32/src/flash/h7.rs
index 7ce0ac776..3f2129de8 100644
--- a/embassy-stm32/src/flash/h7.rs
+++ b/embassy-stm32/src/flash/h7.rs
@@ -39,6 +39,10 @@ pub(crate) unsafe fn blocking_write(offset: u32, buf: &[u8]) -> Result<(), Error
         w.set_psize(2); // 32 bits at once
     });
 
+    cortex_m::asm::isb();
+    cortex_m::asm::dsb();
+    atomic_polyfill::fence(atomic_polyfill::Ordering::SeqCst);
+
     let ret = {
         let mut ret: Result<(), Error> = Ok(());
         let mut offset = offset;
@@ -64,6 +68,10 @@ pub(crate) unsafe fn blocking_write(offset: u32, buf: &[u8]) -> Result<(), Error
 
     bank.cr().write(|w| w.set_pg(false));
 
+    cortex_m::asm::isb();
+    cortex_m::asm::dsb();
+    atomic_polyfill::fence(atomic_polyfill::Ordering::SeqCst);
+
     ret
 }