It's happened that glitches on the STM32_RST and STM32_BOOT lines have put the STM32 companion microcontroller into DFU mode making it not boot its FW, rendering it useless for the user.
Considering that the STM32 companion microcontroller is always reset on a reboot or power cycle, resetting it once again in U-Boot SPL isn't going to hurt it any more.
For ATtiny companion microcontroller, the situation is a bit different because a reboot or power cycle doesn't reset it. Additionally, since it can only be reset with a UPDI reset on the STM32_RST line, and that is virtually impossible to mistakenly trigger, the ATtiny is unlikely to be in unwanted reset or enter reset because U-Boot toggles STM32_RST line.
This series adds this (sometimes) required reset of the MCU in U-Boot SPL on Ringneck PX30 to recover from this unwanted DFU state.
Signed-off-by: Quentin Schulz quentin.schulz@theobroma-systems.com --- Changes in v2: - updated comments to use /**/ form - updated error messages to indicate direction and level - added Heiko's Rb for the second patch - split int ret = gpio_request into two different lines for coding style consistency with the other gpio_request instruction - Link to v1: https://lore.kernel.org/r/20231025-ringneck-stm32-reset-v1-0-052562bec53f@th...
--- Quentin Schulz (2): rockchip: ringneck-px30: always reset STM32 companion controller on boot rockchip: ringneck-px30: enable SPL_BOARD_INIT
.../ringneck_px30/ringneck-px30.c | 53 ++++++++++++++++++++++ configs/ringneck-px30_defconfig | 1 + 2 files changed, 54 insertions(+) --- base-commit: 07fe79c93c5caba181f37844ca95fbda4db3f613 change-id: 20231024-ringneck-stm32-reset-b5b7e7355ae4
Best regards,