TS-7553-V2 U-Boot USB boot
From embeddedTS Manuals
The one addition is to create the tsinit.ub file in the root of the USB drive. In order to do this, a U-Boot script must be created and then converted to the .ub format. This process requires a set of U-Boot specific tools. These are available on most every linux distribution, the instructions below are for Debian, either run on a host PC or on the device itself. See the package installation documentation for other respective distributions.
Install U-Boot tools in Debian
apt-get update && apt-get install u-boot-tools -y
Create the file tsinit.scr in the root of the USB drive with the linux filesystem:
# Prepare with:
# mkimage -A arm -T script -C none -n 'ts7553v2 usb' -d tsinit.scr tsinit.ub
# DO NOT MANUALLY EDIT THE .UB FILE
load usb 0:1 ${fdtaddr} /boot/imx6ul-ts7553v2${variant}.dtb;
load usb 0:1 ${loadaddr} /boot/zImage;
setenv bootargs root=/dev/sda1 ${cmdline_append};
bootz ${loadaddr} - ${fdtaddr};
Then in the same directory generate the tsinit.ub file:
mkimage -A arm -T script -C none -n 'ts7553v2 usb' -d tsinit.scr tsinit.ub