What is an USB Filter Driver?

Question

On HP's web site, I see a driver which is named "AMD USB Filter Driver" What is a USB Filter Driver? What does it do? What happens if I don't install it?

Answer 1

A Filter Driver

is a Microsoft Windows driver that adds value to peripheral devices or supports a specialized device in the personal computer. It is a driver/program/module that is inserted into the existing driver stack to perform some specific function.

Written either by Microsoft or the vendor of the hardware, any number of filter drivers can be added to Windows. Upper level filter drivers sit above the primary driver for the device (the function driver), while lower level filter drivers sit below the function driver and above the bus driver.

You will find some examples at this driver development page
(tho, that might be more useful at a Stackoverflow question).

Here is an example at google groups about writing a USB Filter Driver,
that thread gives a brief discussion on its limitations.
Meanwhile, this Stackoverflow discussion shows a use-case.

Answer 2

Quick googling suggests that it is a patch that fixes USB problems on some old motherboards. If you have no problems with USB devices, you probably don't need to install it.