On Thu, 2016-03-10 at 20:51 +0800, Joseph Chang wrote:
> I did verify to dump EEPROM data and also write EEPROM by per byte.
> 
> 1.Plug dm9601/dm9621 adapter and has get dm9601.ko be 'insmod' to have 'eht0',
> 2.Run ethtool v3.7 (as attached executable file and it's help display.)
> 3. Commands:
>    ./ethtool -e eth0  (dump EEPROM data for all the .get_eeprom_len )
>    ./ethtool -E eth0 magic 0x9620 offset 0 value 0xf1  (write 0xf1 to eeprom byte0)
>    ./ethtool -E eth0 magic 0x9620 offset 1 value 0xf2  (write 0xf2 to eeprom byte1)
>    ./ethtool -E eth0 magic 0x9620 offset 2 value 0xf3  (write 0xf3 to eeprom byte2)
[...]

So you only tested writing 1 byte at a time.  Try again with 3 bytes
and you'll see how it goes wrong.

Ben.

-- 
Ben Hutchings
To err is human; to really foul things up requires a computer.