While using cp210x USB to serial driver and kernel messages saying cp210x_open - Unable to enable UART replace the cp210x module in kernel
The attached module was compiled using the linux-source-3.2.0 (3.0.0-24).
Rename cp210x module according your processor architecture, execute install.sh.
Refer to http://pharos.ece.utexas.edu/wiki/index.php/Fixing_the_cp210x_open_-_Unable_to_enable_UART_Error_-_04/17/2011 
for manual update or use makeCP210x.sh script.
Starting with Kernel 3.2.0.26 this update is obsolete and the module can be used without modification.