I'm developing product based on imx6sl SoC. I've got question how to correctly manage initial boot scenarios. I'm using u-boot image stored in SPI NOR flash. It performs normal boot. But sometimes I will want to return into SDP (Serial Downloader) mode for purpose upload manufacturing images and perform necessary software updates.
Final device will not contain mechanical switches for BOOT_MODE and will have fuses programmed for boot from SPI NOR flash. There will no possibility tweak board to switch it into SDP mode.
My question is there any possibility to fallback into SDP mode from the loaded u-boot image? Eg. by checking in u-boot some `magic` key combination emulate fail-state in u-boot and tell cpu return to SDP mode.
Probably you may advice some alternate solution to perform safe updates of working system?
Thank you very much!