Please look up your sensor in the list of supported devices.
setenv bootargs 'mem=${osmem:-32M} console=ttyAMA0,115200 panic=20 root=/dev/mtdblock3 rootfstype=squashfs init=/init mtdparts=sfc:256k(boot),64k(env),2048k(kernel),5120k(rootfs),-(rootfs_data)'
setenv bootcmd 'setenv setargs setenv bootargs ${bootargs}; run setargs; sf probe 0; sf read 0x42000000 0x50000 0x200000; bootm 0x42000000'
setenv uk 'mw.b 0x42000000 ff 1000000; tftp 0x42000000 uImage.${soc} && sf probe 0; sf erase 0x50000 0x200000; sf write 0x42000000 0x50000 ${filesize}'
setenv ur 'mw.b 0x42000000 ff 1000000; tftp 0x42000000 rootfs.squashfs.${soc} && sf probe 0; sf erase 0x250000 0x500000; sf write 0x42000000 0x250000 ${filesize}'
saveenv
setenv soc gk7xxxxxxx # Set your SoC. gk7202v300, gk7205v200, or gk7205v300.
setenv osmem 32M
setenv totalmem 64M # 64M for gk7202v300, gk7205v200, 128M for gk7205v300.
setenv ipaddr 192.168.1.10
setenv serverip 192.168.1.254 # Your TFTP server IP address.
saveenv
run uk; run ur; reset # Flash kernel, rootfs and reboot device
run uk; run ur; reset
echo -e "!/bin/sh\n\ndevmem 0x120100f0 32 0x19\n" >/etc/init.d/S96trick
chmod +x /etc/init.d/S96trick
Alternative way here
You always have an option to update the bootloader. However, you need to understand what you do.
NB! Replace bootloader filename with the one matching your SoC. Full list is here.
mw.b 0x42000000 ff 1000000
tftp 0x42000000 u-boot-gk7xxxxxxxx-beta.bin
sf probe 0
sf erase 0x0 0x50000
sf write 0x42000000 0x0 ${filesize}
reset