Official uboot is very different from the mediatek uboot, not that easy to use but very flexible.

For example, if my firmware stored in USB disk and I want to update firmware from uboot, I will need to load from usb disk to memory first, then erase flash and write to it all by command.

1. usb start this will enable usb
2. fatload usb 0:0 0x81000000 root_uImage my firmware name is root_uImage, and I load it to 0x81000000 (DDR memory address)
3. sf start this will enable spi flash
4. sf erase 0x50000 0xfb0000 erase the firmware partition, from 0x50000 and size is 0xfb0000
5. sf write 0x81000000 0x50000 0x600325 read from 0x81000000 and write to SPI flash 0x50000, size is 0x600325(6292261), this size we can find at fatload.

Here is the log:

U-Boot 2022.01 (Oct 29 2022 - 14:39:20 +0000)                                   
                                                                                
resetctl_reboot resetctl-reboot: set_state_simple op missing                    
mtmips-reset rstctrl@0x34: set_state_simple op missing                          
CPU:   MediaTek MT7628A ver:1 eco:2                                             
Boot:  DDR2, SPI-NOR 3-Byte Addr, CPU clock from XTAL                           
Clock: CPU: 580MHz, Bus: 193MHz, XTAL: 40MHz                                    
DRAM:  128 MiB                                                                  
pinconfig pin_state: set_state_simple op missing                                
simple_bus palmbus@10000000: set_state_simple op missing                        
mt7628-clk clkctrl@0x2c: set_state_simple op missing                            
mt762x_wdt watchdog@100: set_state_simple op missingg                           
WDT:   Started watchdog@100 with servicing (60s timeout)                        
MMC:   fixed_clock clk48m@0: set_state_simple op missing                        
pinconfig sd_iot_mode: set_state_simple op missing                              
mmc@10130000: 0                                                                 
Loading Environment from SPIFlash... mt7621_spi spi@b00: set_state_simple op mig
mt7621_spi spi@b00: spi_find_chip_select: plat=86fa0258, cs=0                   
jedec_spi_nor spi-flash@0: set_state_simple op missing                          
SF: Detected w25q128 with page size 256 Bytes, erase size 4 KiB, total 16 MiB   
jedec_spi_nor spi-flash@0: from 0x00030000, len 4096                            
OK                                                                              
In:    uart2@e00                                                                
Out:   uart2@e00                                                                
Err:   uart2@e00                                                                
Net:   pinconfig ephy_iot_mode: set_state_simple op missing                     
mtmips-reset rstctrl@0x34: set_state_simple op missing                          
                                                                                
Warning: eth@10110000 (eth0) using random MAC address - ce:78:14:4e:a5:ac       
eth0: eth@10110000                                                              
Hit any key to stop autoboot:  0                                                
=>                                                                              
=> usb start                                                                    
starting USB...                                                                 
Bus ehci@101c0000: ehci_generic ehci@101c0000: set_state_simple op missing      
mt76x8_usb_phy usb-phy@10120000: set_state_simple op missing                    
USB EHCI 1.00                                                                   
scanning bus ehci@101c0000 for devices... usb_hub usb_hub: set_state_simple op g
2 USB Device(s) found                                                           
       scanning usb for storage devices... 1 Storage Device(s) found            
=> fatload usb 0:0 0x81000000 root_uImage                                       
6292261 bytes read in 245 ms (24.5 MiB/s)                                       
=> sf start                                                                     
No SPI flash selected. Please run `sf probe'                                    
=> sf probe                                                                     
mt7621_spi spi@b00: spi_find_chip_select: plat=86fa0258, cs=0                   
mt7621_spi spi@b00: spi_find_chip_select: plat=86fa0258, cs=0                                                                                                   
=> sf erase 0x50000 0xfb0000                                                    
jedec_spi_nor spi-flash@0: at 0x50000, len 16449536   
SF: 16449536 bytes @ 0x50000 Erased: OK
=> sf write 0x81000000 0x50000 0x600325
device 0 offset 0x50000, size 0x600325
jedec_spi_nor spi-flash@0: to 0x00050000, len 6292261
SF: 6292261 bytes @ 0x50000 Written: OK