HTC Vision Overclock Module
Michael Huang (coolbho3k)

This kernel module is capable of changing the maximum CPU speed of MSM7x30 and
8x55 devices running Android, such as the HTC Vision and the T-Mobile G2. The
current default presets are for T-Mobile G2 with HTC kernel 2.6.32.17, but the
module can easily be modified to run on any device with the MSM7x30 or 8x55
SoCs.

To use it on a T-Mobile G2 with HTC kernel 2.6.32.17, run:

insmod vision_oc.ko

This will by default overclock the phone to 1017.6MHz at 1200mV. To overclock
higher, run:

insmod vision_oc.ko pll2_l_val=53

Where pll2_l_val equals the speed you want the phone to run in MHz (in this
case, 1017.6MHz again) divided by 19.2. My G2 runs at 1420.8MHz (pll_l_val=74)
with relative stability.

To also change the voltage at the highest speed, run:

insmod vision_oc.ko pll2_l_val=X vdd_mv=1200 vdd_raw=242

Where vdd_mv equals the voltage in mV and vdd_raw equals 224+(vdd_mv-750)/25.

If you are not running a T-Mobile G2 with HTC kernel 2.6.32.17, you MUST also
give the kernel some other configuration options too! Pull the file
/proc/kallsyms and search for the address values of acpu_freq_tbl and 
perflock_notifier_call. When loading the module, specify these addresses along
with any other parameters:

insmod vision_oc.ko acpu_freq_tbl_addr=0xc055e1a0
perflock_notifier_call_addr=0xc006c974

I highly recommend that you use SetCPU to limit the clock speed while the
screen is off to 768MHz to prevent the phone from scaling up too high.
Without the ability to flash custom kernels, we cannot add intermediate steps
between 768MHz and the overclocked speed.