Petr Tesarik - 2013-07-04

This is probably just poorly documented. The CP2102 does not have any command in its protocol to modify the vendor string. You may notice that the official CP210xManufacturing.DLL from SiLabs does not provide any function in the API to modify the vendor string either.

However, since the vendor string is stored in the EEPROM, you can still set it by specifying '--force-eeprom'. But keep in mind that poking around the EEPROM directly is slightly more likely to brick your CP2102 than using the standard protocol commands. ;-)