stm32/mboot: Only exit on timeout if application valid.

Check application validity before exiting bootloader due to timeout.
If application is invalid, disable timeout and remain in bootloader
indefinitely to avoid reset loop.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

ports/stm32/mboot/main.c

@@ -1745,7 +1745,14 @@ void stm32_main(uint32_t initial_r0) {
         // Capture systick_ms once to avoid race condition with ISR
         uint32_t current_ms = systick_ms;
         if (dfu_context.timeout_active && current_ms >= MBOOT_DFU_TIMEOUT_MS) {
-            dfu_context.leave_dfu = true;
+            // Only exit if application is valid (avoid reset loop with invalid app)
+            uint32_t msp = *(volatile uint32_t *)APPLICATION_ADDR;
+            if ((msp & APP_VALIDITY_BITS) == 0) {
+                dfu_context.leave_dfu = true;
+            } else {
+                // Application invalid, disable timeout and stay in bootloader
+                dfu_context.timeout_active = false;
+            }
         }
         #endif
     }