There's a lot of problems with USB stack on Rapsberry Pi and developers are working hard to fix as many of them as possible. They introduce some kernel modules options (like
dwc_otg.fiq_fix_enable) that enables those fixes from time to time. Most of them are being enabled by default in recent kernels so you don't want to know them in order to use them. It's always good to know what you can disable when troubleshooting problems, though. And it's good to know that you don't need them in your cmdline.txt anymore when cleaning it up or reinstalling your SD card.
So what is the list of all such options that and what is their meaning?