Long boot: 5s until U-Boot gets running


Looking at the boot trace using the serial output, it takes roughly 5s after power-on until the first trace is seen, that’s U-Boot gets running.
I’m wondering if this time is spend looking for USB boot, or something else (I’m using a power supply so no data connection, but the delay is the same if I power it from a PC USB port)?
I’d like to reduce this as much as possible, any hints if this is possible?


The AM57xx checks a few pins at boot time to set the boot sources. These are called “SYSBOOT” pins in the AM57xx Technical Reference Manual. On the Bone-AI these pins are configured to choose USB first, then SD, then eMMC. So out of the box it checks two sources before booting from internal memory.

The only way to change this is to change the resistor pull options on the hardware.