Ftrace: tracing init call of out of tree modules

Hi, I am learning ftrace. I would like to know to use frace filters for tracing a module's init function. For example, assume the module uvcvideo. While the module is loaded, cat available_filter_functions | grep uvcvideo will give me a big list of functions. Then I enable those functions by setting ftrace filter with: echo "uvc*" > set_ftrace_filter However, as soon as I rmmod the driver, set_ftrace_filter becomes empty automatically. So how do I do a trace on out-of-tree modules I have ? -- Thanks and Regards, Aurabindo J