Originally Posted by rvckumar
Thanks. But I need to debug a host driver that is already supplied by the vendor and I want to have idea of the host driver execution flow.
I have searched google / books, but I found the lot of docs for USB device driver writing only. Thats why I seek the help from linux community.
If you mean the linux USB host driver (singular, since there is only one of each flavour), that is part of the official kernel source and you should contact the official maintainers named in the code.
If you are using something else I think you are gonna have a tough time; the documentation for (linux specific) USB driver programming is not even that extensive, beyond a few books, and the books I have do not bother with the host controller since it already exists. However, there is much interaction with the host controller, so depending on how extensive this debugging task is, you may need to get a grasp on that first.