Data storage device and method for rewriting parameters thereof

A data storage device comprising:

• a flash memory storing a firmware, wherein the firmware comprises a plurality of mode page settings, and each mode page setting comprises a plurality of mode parameters;
• and
• a controller receiving a mode selection command and a data out message from a host, wherein the data out message is arranged to rewrite a first mode page setting among the plurality of mode page settings, and further determining whether the data out message will change mode parameters which cannot be rewritten in the first mode page setting according to the data out message and the first mode page setting by performing bitwise logic operations on a new mode page setting in the data out message, preset values of the plurality of mode parameters of the first mode page setting, and a rewriteable setting for each bit of the first mode page setting,
• wherein in response to each bit of results of the bitwise logic operations being a zero value, the controller determines that the data out message will not change the mode parameters which cannot be rewritten in the first mode page setting, and determines whether a plurality of new mode parameters are kept in the flash memory after the data storage device is turned off according to the mode selection command.