Booting from usb (after uboot)

I’m trying to boot from usb after loading uboot from mmc.

Im using Ubuntu image from allwinner target, 22.04

Grub loads from usb and loads the kernel and the initramfs to memory.
but then the activity light on the disk goes dark and the kernel drops to initramfs saying it could not find the disk.

Closer inspection shows that there are no usb devices at that stage.

What do i need to add to the initramfs or grub.conf to make it understand that soc 4200000 is a usb device?