From b760f5fc9db0f4e1c9ffeceef9233a8041dd5169 Mon Sep 17 00:00:00 2001
From: Robert Fisk <robert_fisk@fastmail.fm>
Date: Sun, 21 Aug 2016 09:37:11 +1200
Subject: [PATCH] Fix for occasional timeout on writes...

...Downstream was not always changing state correctly after closely
spaced interrupts.

Also improve flash-write-lockout function to avoid dependency on
optimisation level.

Conflicts:
	Upstream/Src/interrupts.c
---
 Downstream/Src/interrupts.c | 12 +++++++++---
 Downstream/Src/main.c       | 27 +++++++++++++++++----------
 Upstream/Src/interrupts.c   | 23 ++++++++++++++---------
 Upstream/Src/main.c         | 17 +++++++----------
 4 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/Downstream/Src/interrupts.c b/Downstream/Src/interrupts.c
index 3d88c18..147ba29 100644
--- a/Downstream/Src/interrupts.c
+++ b/Downstream/Src/interrupts.c
@@ -46,6 +46,8 @@ extern HCD_HandleTypeDef hhcd_USB_OTG_FS;
 extern DMA_HandleTypeDef hdma_spi1_rx;
 extern DMA_HandleTypeDef hdma_spi1_tx;
 
+extern volatile uint8_t UsbInterruptHasHappened;
+
 uint8_t BusFaultAllowed = 0;
 
 
@@ -83,9 +85,8 @@ void DMA2_Stream3_IRQHandler(void)
 
 void OTG_FS_IRQHandler(void)
 {
-    //INT_ACTIVE_ON;
     HAL_HCD_IRQHandler(&hhcd_USB_OTG_FS);
-    //INT_ACTIVE_OFF;
+    UsbInterruptHasHappened = 1;
 }
 
 
@@ -93,6 +94,11 @@ void OTG_FS_IRQHandler(void)
 //The deliberate flash lockout will cause a bus fault that we need to process.
 void EnableOneBusFault(void)
 {
+    //It should not be enabled already!
+    if (BusFaultAllowed)
+    {
+        while (1);
+    }
     SCB->SHCSR = SCB_SHCSR_BUSFAULTENA_Msk;
     BusFaultAllowed = 1;
 }
@@ -104,7 +110,7 @@ void BusFault_Handler(void)
         BusFaultAllowed = 0;
         return;
     }
-    while(1);
+    while (1);
 }
 
 
diff --git a/Downstream/Src/main.c b/Downstream/Src/main.c
index 3dbd865..2d6e9fa 100644
--- a/Downstream/Src/main.c
+++ b/Downstream/Src/main.c
@@ -44,16 +44,17 @@
 
 
 /* Private function prototypes -----------------------------------------------*/
-void SystemClock_Config(void);
+static void SystemClock_Config(void);
 static void GPIO_Init(void);
-void DisableFlashWrites(void);
-void CheckFirmwareMatchesHardware(void);
+static void DisableFlashWrites(void);
+static void CheckFirmwareMatchesHardware(void);
+
+volatile uint8_t    UsbInterruptHasHappened = 0;
+uint8_t             IterationCount = 0;
 
 
 int main(void)
 {
-    uint32_t iterationCount = 0;
-
     //First things first!
     DisableFlashWrites();
     CheckFirmwareMatchesHardware();
@@ -77,12 +78,17 @@ int main(void)
         Downstream_SPIProcess();
         Downstream_PacketProcessor_CheckNotifyDisconnectReply();
 
+        //Count number of main loops since last USB interrupt
+        if (UsbInterruptHasHappened)
+        {
+            UsbInterruptHasHappened = 0;
+            IterationCount = 0;
+        }
+
         //Some USB host state transitions take 3 iterations to fully apply.
         //We'll be generous and give it 5 before sleeping.
-        iterationCount++;
-        if (iterationCount > 4)
+        if (IterationCount++ > 4)
         {
-            iterationCount = 0;
             __WFI();                //sleep time!
         }
     }
@@ -97,10 +103,11 @@ void DisableFlashWrites(void)
     FLASH->KEYR = 999;
 
     //Confirm that flash cannot be unlocked
-    //This unlock attempt will also cause a bus fault.
-    EnableOneBusFault();
+    //This unlock attempt will also cause two bus faults.
     if ((FLASH->CR & FLASH_CR_LOCK) == 0) while(1);
+    EnableOneBusFault();
     FLASH->KEYR = FLASH_KEY1;
+    EnableOneBusFault();
     FLASH->KEYR = FLASH_KEY2;
     if ((FLASH->CR & FLASH_CR_LOCK) == 0) while(1);
 }
diff --git a/Upstream/Src/interrupts.c b/Upstream/Src/interrupts.c
index 3da4f86..ff902f0 100755
--- a/Upstream/Src/interrupts.c
+++ b/Upstream/Src/interrupts.c
@@ -75,17 +75,17 @@ void OTG_FS_IRQHandler(void)
 }
 
 void DMA2_Stream2_IRQHandler(void)
-{
-    INT_ACTIVE_ON;
-    HAL_DMA_IRQHandler(&spiRxDmaHandle);
-    INT_ACTIVE_OFF;
+{
+    INT_ACTIVE_ON;
+    HAL_DMA_IRQHandler(&spiRxDmaHandle);
+    INT_ACTIVE_OFF;
 }
 
 void DMA2_Stream3_IRQHandler(void)
-{
-    INT_ACTIVE_ON;
-    HAL_DMA_IRQHandler(&spiTxDmaHandle);
-    INT_ACTIVE_OFF;
+{
+    INT_ACTIVE_ON;
+    HAL_DMA_IRQHandler(&spiTxDmaHandle);
+    INT_ACTIVE_OFF;
 }
 
 void EXTI3_IRQHandler(void)
@@ -101,6 +101,11 @@ void EXTI3_IRQHandler(void)
 //The deliberate flash lockout will cause a bus fault that we need to process.
 void EnableOneBusFault(void)
 {
+    //It should not be enabled already!
+    if (BusFaultAllowed)
+    {
+        while (1);
+    }
     SCB->SHCSR = SCB_SHCSR_BUSFAULTENA_Msk;
     BusFaultAllowed = 1;
 }
@@ -112,7 +117,7 @@ void BusFault_Handler(void)
         BusFaultAllowed = 0;
         return;
     }
-    while(1);
+    while (1);
 }
 
 
diff --git a/Upstream/Src/main.c b/Upstream/Src/main.c
index 83444ee..ee48bab 100755
--- a/Upstream/Src/main.c
+++ b/Upstream/Src/main.c
@@ -44,15 +44,11 @@
 #include "interrupts.h"
 
 
-/* Private variables ---------------------------------------------------------*/
-
-
-
 /* Private function prototypes -----------------------------------------------*/
-void SystemClock_Config(void);
-void GPIO_Init(void);
-void DisableFlashWrites(void);
-void CheckFirmwareMatchesHardware(void);
+static void SystemClock_Config(void);
+static void GPIO_Init(void);
+static void DisableFlashWrites(void);
+static void CheckFirmwareMatchesHardware(void);
 
 
 
@@ -92,10 +88,11 @@ void DisableFlashWrites(void)
     FLASH->KEYR = 999;
 
     //Confirm that flash cannot be unlocked
-    //This unlock attempt will also cause a bus fault.
-    EnableOneBusFault();
+    //This unlock attempt will also cause two bus faults.
     if ((FLASH->CR & FLASH_CR_LOCK) == 0) while(1);
+    EnableOneBusFault();
     FLASH->KEYR = FLASH_KEY1;
+    EnableOneBusFault();
     FLASH->KEYR = FLASH_KEY2;
     if ((FLASH->CR & FLASH_CR_LOCK) == 0) while(1);
 }