mimxrt/flash: Swap the order of disabling IRQ and disabling the cache.

robert-hh · dpgeorge · commit 2a80d5c68b5e · 2025-02-10T11:31:28.000+11:00
This change stopped problems with USB IRQ happening during flash writes.

Signed-off-by: robert-hh &lt;robert@hammelrath.com&gt;
diff --git a/ports/mimxrt/flash.c b/ports/mimxrt/flash.c
@@ -43,14 +43,13 @@ void flash_init(void) {
 __attribute__((section(".ram_functions"))) status_t flash_erase_block(uint32_t erase_addr) {
     status_t status = kStatus_Fail;
 
-    SCB_CleanInvalidateDCache();
-    SCB_DisableDCache();
     __disable_irq();
+    SCB_DisableDCache();
 
     status = flexspi_nor_flash_erase_block(BOARD_FLEX_SPI, erase_addr);
 
-    __enable_irq();
     SCB_EnableDCache();
+    __enable_irq();
 
     return status;
 }
@@ -60,14 +59,13 @@ __attribute__((section(".ram_functions"))) status_t flash_erase_block(uint32_t e
 __attribute__((section(".ram_functions"))) status_t flash_erase_sector(uint32_t erase_addr) {
     status_t status = kStatus_Fail;
 
-    SCB_CleanInvalidateDCache();
-    SCB_DisableDCache();
     __disable_irq();
+    SCB_DisableDCache();
 
     status = flexspi_nor_flash_erase_sector(BOARD_FLEX_SPI, erase_addr);
 
-    __enable_irq();
     SCB_EnableDCache();
+    __enable_irq();
 
     return status;
 }
@@ -83,10 +81,6 @@ __attribute__((section(".ram_functions"))) status_t flash_write_block(uint32_t d
     if (length == 0) {
         status = kStatus_Success;  // Nothing to do
     } else {
-
-        SCB_CleanInvalidateDCache();
-        SCB_DisableDCache();
-
         // write data in chunks not crossing a page boundary
         do {
             next_addr = dest_addr - (dest_addr % PAGE_SIZE_BYTES) + PAGE_SIZE_BYTES; // next page boundary
@@ -96,7 +90,11 @@ __attribute__((section(".ram_functions"))) status_t flash_write_block(uint32_t d
             }
 
             __disable_irq();
+            SCB_DisableDCache();
+
             status = flexspi_nor_flash_page_program(BOARD_FLEX_SPI, dest_addr, (uint32_t *)src, write_length);
+
+            SCB_EnableDCache();
             __enable_irq();
 
             // Update remaining data length
@@ -106,9 +104,6 @@ __attribute__((section(".ram_functions"))) status_t flash_write_block(uint32_t d
             src += write_length;
             dest_addr += write_length;
         } while ((length > 0) && (status == kStatus_Success));
-
-        SCB_EnableDCache();
-
     }
     return status;
 }
