This will show you how to find out all about parameter options on your system
If you view the config file in /boot and search for either IOMMU or USB you will see the huge range of possible parameter choices, most of which are irrelevent. There seems to be no recipe for finding the parameters relevant to a given problem
There is also a kernel.org document
https://www.kernel.org/doc/Documentation/x86/x86_64/boot-options.txt
it seems incomplete to me, but it does give some information
The absolute full list is here
https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html