QUERY · ISSUE

[mboot] It will stay in the dfu mode forever and not reset

openby rolandvsopened 2020-02-24updated 2025-11-09

port-stm32needs-info

When using mboot to replace the code with dfu commands all works fine. However, mboot stays in dfu mode and not resetting the device. This is tested using mboot with the H743.

CANDIDATE · PULL REQUEST

stm32/mboot: Leave bootloader from thread mode, not from IRQ.

mergedby dpgeorgeopened 2021-05-19updated 2021-05-20

port-stm32

Leaving the bootloader from an IRQ (eg USB or I2C IRQ) will not work if MBOOT_LEAVE_BOOTLOADER_VIA_RESET is disabled, ie if mboot jumps directly to the application. This is because the CPU will still be in IRQ state when the application starts and IRQs of lower priority will be blocked.

Fix this by setting a flag when the bootloader should finish, and exit the bootloader always from the main (top level) thread.

This also improves the USB behaviour of mboot: it no longer abruptly disconnects when the manifest command is sent.

Assessment

S Sonnet · medium

The issue reports mboot staying in DFU mode and not resetting after firmware upload on STM32 H743. The PR fixes bootloader exit from IRQ context, which directly causes the bootloader to fail to leave DFU mode - when the manifest command is processed in an IRQ handler and MBOOT_LEAVE_BOOTLOADER_VIA_RESET is disabled, the exit doesn't work and the device stays in the bootloader. The PR also explicitly mentions fixing USB behaviour so mboot "no longer abruptly disconnects when the manifest command is sent," which maps to the symptom of staying in DFU mode. However, the issue specifically says "not resetting" while the PR's primary fix is for the non-reset (direct jump) code path, so there's uncertainty about whether the reporter's H743 configuration matches exactly.

Suggested action

Close issue #5693 as likely resolved by PR #7283 if merged. Ask reporter to confirm whether the fix resolves their H743 case, noting the PR addresses bootloader exit from IRQ context which is the most probable root cause of staying in DFU mode.

[mboot] It will stay in the dfu mode forever and not reset

stm32/mboot: Leave bootloader from thread mode, not from IRQ.

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