Switching boot source on SOPINE64

[xalius]

The A64 will probe the mmc/spi interfaces in a set sequence, sdcard has priority over eMMC, so it depends where you have a valid boot0/spl loader. You can also install u-boot into the SPI flash and boot from network or USB for example. If no valid boot source is found, it will fall back into FEL bootloader mode which is communicating viat the USB OTG port. This can be used to upload u-boot for example and then boot or expose eMMC as USB mass storage...

Code:

boot-> check fel key pressed (yes)--> FEL mode (boot from USB OTG)
                         \  
                     (no) \
                           \-------> 1) try to boot from SMHC0 (SD card)
                                     2) try to boot from SMHC2 (eMMC)
                                     3) try to boot from SPI0 (SPI NOR Flash)
                                     4) FEL mode (boot from USB OTG)