Merge #1014

1014: Add memory barriers to H7 flash driver to mitigate PGSERR errors r=lulf a=matoushybl

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.

Without the barrier, the PG bit is not set, when the writes are being done, resulting in an error.

Co-authored-by: Matous Hybl <hyblmatous@gmail.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/embassy-stm32/src/flash/h7.rs b/embassy-stm32/src/flash/h7.rs
index 7ce0ac77..3f2129de 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
 }