u-boot boot linux from usb

u-boot-usb.txt

env set bootcmd_usb "run findfdt; usb start; if run loadimage_usb; then run usbboot; fi"
env set loadfdt_usb "fatload usb ${usbdev}:${usbpart} ${fdt_addr} ${fdt_file}"
env set loadimage_usb "fatload usb ${usbdev}:${usbpart} ${loadaddr} ${image}"
env set usbargs "setenv bootargs console=${console},${baudrate} root=${usbroot}"
env set usbboot "echo Booting from usb ...; run usbargs; if run loadfdt_usb; then bootz ${loadaddr} - ${fdt_addr}; else echo WARN: Cannot load the DT; fi"
env set usbdev 0
env set usbpart 1
env set usbroot "/dev/sda2 rootwait rw"
run bootcmd_usb

U-Boot 2020.07-2 (Aug 09 2020 - 02:00:40 +0000) Arch Linux ARM

DRAM: 3.9 GiB
RPI 4 Model B (0xc03111)
MMC: emmc2@7e340000: 0, mmcnr@7e300000: 1
Loading Environment from FAT... *** Warning - bad CRC, using default environment

In: serial
Out: vidconsole
Err: vidconsole
Net: eth0: genet@7d580000
starting USB...
No working controllers found
Hit any key to stop autoboot: 1

U-Boot 2020.07-2 (Aug 09 2020 - 02:00:40 +0000) Arch Linux ARM

DRAM: 3.9 GiB
RPI 4 Model B (0xc03111)
MMC: emmc2@7e340000: 0, mmcnr@7e300000: 1
Loading Environment from FAT... *** Warning - bad CRC, using default environment

In: serial
Out: vidconsole
Err: vidconsole
Net: eth0: genet@7d580000
starting USB...
No working controllers found
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found U-Boot script /boot.scr
645 bytes read in 20 ms (31.3 KiB/s)

Executing script at 02c00000

Error: "findfdt" not defined

starting USB...
No working controllers found
SCRIPT FAILED: continuing...
Card did not respond to voltage select!
starting USB...
No working controllers found
USB is stopped. Please issue 'usb start' first.
starting USB...
No working controllers found