From 2c62e262b2c84b077355d67c6302bd02f6a28552 Mon Sep 17 00:00:00 2001
From: stevie67
Date: Sat, 4 Jan 2014 03:02:32 +0100
Subject: Fix issue #62: Cache loses data

Use the storage cache not only for writing but also for reading. This
avoids reading stale data and thus data loss.
---
 stm/storage.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

(limited to 'stm')

diff --git a/stm/storage.c b/stm/storage.c
index 6878de22e..7342a53ac 100644
--- a/stm/storage.c
+++ b/stm/storage.c
@@ -49,6 +49,16 @@ static uint8_t *cache_get_addr_for_write(uint32_t flash_addr) {
     return (uint8_t*)CACHE_MEM_START_ADDR + flash_addr - flash_sector_start;
 }
 
+static uint8_t *cache_get_addr_for_read(uint32_t flash_addr) {
+    uint32_t flash_sector_start;
+    uint32_t flash_sector_size;
+    uint32_t flash_sector_id = flash_get_sector_info(flash_addr, &flash_sector_start, &flash_sector_size);
+    if (cache_flash_sector_id == flash_sector_id)
+        return (uint8_t*)CACHE_MEM_START_ADDR + flash_addr - flash_sector_start;
+    // not in cache, copy straight from flash
+    return (uint8_t*)flash_addr;
+}
+
 void storage_init(void) {
     if (!is_initialised) {
         cache_flash_sector_id = 0;
@@ -131,8 +141,8 @@ bool storage_read_block(uint8_t *dest, uint32_t block) {
         return true;
 
     } else if (FLASH_PART1_START_BLOCK <= block && block < FLASH_PART1_START_BLOCK + FLASH_PART1_NUM_BLOCKS) {
-        // non-MBR block, just copy straight from flash
-        uint8_t *src = (uint8_t*)FLASH_MEM_START_ADDR + (block - FLASH_PART1_START_BLOCK) * BLOCK_SIZE;
+        uint32_t flash_addr = FLASH_MEM_START_ADDR + (block - FLASH_PART1_START_BLOCK) * BLOCK_SIZE;
+        uint8_t *src = cache_get_addr_for_read(flash_addr);
         memcpy(dest, src, BLOCK_SIZE);
         return true;
 
-- 
cgit v1.2.3


From 2a5e6538b941d1fc9c1c0ef0bb0827b5ed2425d2 Mon Sep 17 00:00:00 2001
From: Damien George
Date: Sat, 4 Jan 2014 12:34:36 +0000
Subject: stm: Add comments for storage read from cache.

---
 stm/storage.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'stm')

diff --git a/stm/storage.c b/stm/storage.c
index 7342a53ac..daee4adb5 100644
--- a/stm/storage.c
+++ b/stm/storage.c
@@ -53,8 +53,10 @@ static uint8_t *cache_get_addr_for_read(uint32_t flash_addr) {
     uint32_t flash_sector_start;
     uint32_t flash_sector_size;
     uint32_t flash_sector_id = flash_get_sector_info(flash_addr, &flash_sector_start, &flash_sector_size);
-    if (cache_flash_sector_id == flash_sector_id)
+    if (cache_flash_sector_id == flash_sector_id) {
+        // in cache, copy from there
         return (uint8_t*)CACHE_MEM_START_ADDR + flash_addr - flash_sector_start;
+    }
     // not in cache, copy straight from flash
     return (uint8_t*)flash_addr;
 }
@@ -141,6 +143,7 @@ bool storage_read_block(uint8_t *dest, uint32_t block) {
         return true;
 
     } else if (FLASH_PART1_START_BLOCK <= block && block < FLASH_PART1_START_BLOCK + FLASH_PART1_NUM_BLOCKS) {
+        // non-MBR block, get data from flash memory, possibly via cache
         uint32_t flash_addr = FLASH_MEM_START_ADDR + (block - FLASH_PART1_START_BLOCK) * BLOCK_SIZE;
         uint8_t *src = cache_get_addr_for_read(flash_addr);
         memcpy(dest, src, BLOCK_SIZE);
-- 
cgit v1.2.3