From d7ce823d79d5fac4194d7bc6f25b160df7f6718e Mon Sep 17 00:00:00 2001
From: xoviat <xoviat@users.noreply.github.com>
Date: Tue, 3 Oct 2023 17:47:29 -0500
Subject: [PATCH] wpan: fix ipcc delay

---
 embassy-stm32/src/ipcc.rs   | 36 ++++++++++++++++--------------------
 embassy-stm32/src/rcc/bd.rs |  2 ++
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/embassy-stm32/src/ipcc.rs b/embassy-stm32/src/ipcc.rs
index e100ca5c..da301a71 100644
--- a/embassy-stm32/src/ipcc.rs
+++ b/embassy-stm32/src/ipcc.rs
@@ -93,15 +93,26 @@ pub struct Ipcc;
 
 impl Ipcc {
     pub fn enable(_config: Config) {
+        // TODO: move these lines to the rcc mod
+
+        // set LPTIM1 & LPTIM2 clock source
+        crate::pac::RCC.ccipr().modify(|w| {
+            w.set_lptim1sel(0b00); // PCLK
+            w.set_lptim2sel(0b00); // PCLK
+        });
+
+        // set RF wake-up clock = LSE
+        crate::pac::RCC.csr().modify(|w| w.set_rfwkpsel(0b01));
+
         IPCC::enable();
         IPCC::reset();
+        // insert bus access and fence for delay
+        IPCC::enable();
+
+        compiler_fence(Ordering::SeqCst);
         IPCC::set_cpu2(true);
 
-        _configure_pwr();
-
-        let regs = IPCC::regs();
-
-        regs.cpu(0).cr().modify(|w| {
+        IPCC::regs().cpu(0).cr().modify(|w| {
             w.set_rxoie(true);
             w.set_txfie(true);
         });
@@ -263,18 +274,3 @@ pub(crate) mod sealed {
         fn state() -> &'static State;
     }
 }
-
-fn _configure_pwr() {
-    // TODO: move the rest of this to rcc
-    let rcc = crate::pac::RCC;
-
-    // TODO: required
-    // set RF wake-up clock = LSE
-    rcc.csr().modify(|w| w.set_rfwkpsel(0b01));
-
-    // set LPTIM1 & LPTIM2 clock source
-    rcc.ccipr().modify(|w| {
-        w.set_lptim1sel(0b00); // PCLK
-        w.set_lptim2sel(0b00); // PCLK
-    });
-}
diff --git a/embassy-stm32/src/rcc/bd.rs b/embassy-stm32/src/rcc/bd.rs
index cec2ea01..aaaf486d 100644
--- a/embassy-stm32/src/rcc/bd.rs
+++ b/embassy-stm32/src/rcc/bd.rs
@@ -143,6 +143,8 @@ impl BackupDomain {
             Self::modify(|w| {});
 
             trace!("BDCR ok: {:08x}", Self::read().0);
+
+            compiler_fence(Ordering::SeqCst);
             return;
         }