From Canon Malaysia
Firmware Version 2.1.2 incorporates the following change.
1. Optimizes the camera’s performance when using certain UDMA 7-compatible CF cards released in February 2012 or later.
The Version 2.1.2 firmware being released this time is for cameras with firmware up to Version 2.1.1. If the camera’s firmware is already Version 2.1.2, it is not necessary to update the firmware.