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	Trace-cmd plugin for parsing USB 3.0 host controller driver traces
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This plugin can be used to report in a human readable format some xhci traces
that trace raw byte arrays by parsing and displaying the raw bytes registered
in the entry structure of the trace ring buffer in a human readable way.

To use the plugin_xhci.py, you need first to download and install the
trace-cmd tool:

$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git
$ cd trace-cmd
$ make && sudo make install

The above command will install trace-cmd by default in /usr/local/bin.
If you want to install it in another directory do, instead:

$ make prefix=<dir> install

Place the plugin_xhci.py file, in the plugins directory.
The plugins directory can be found by default in the directory
/usr/local/lib/trace-cmd/plugins, otherwise if you have set another
directory, in <dir>/lib/trace-cmd/plugins.

To view the list of available xhci trace events do:

$ trace-cmd list | grep xhci-hcd

To start recording, for example, the xhci-hcd:xhci_cmd_completion event do:

$ trace-cmd record -e xhci-hcd:xhci_cmd_completion

This command will create a trace.dat file, in your current directory,
where the trace output is written.
Enter Ctrl-C to disable the trace event.

Then, to view the generated traces, do:

$ trace-cmd report

This command will load the xhci_plugin.py and if there is a handler
implemented for the recorded trace event, this handler will be used
to parse the trace output recorded in trace.dat and will display in
the console the formatted output.

In case that there is no handler implemented, the trace output will be
displayed using the default ftrace printk as defined in the corresponding
trace event's DECLARE_EVENT_CLASS TP_printk macro. To see the default format,
do:

$ trace-cmd report -N

To view the raw content of the ring buffer entry's fields, do:

$ trace-cmd report -R

If you want to see both the address debug messages and the address context
you can do:

$ trace-cmd record -e xhci-hcd:*address*

If you want to enable all xhci events do:

$ trace-cmd record -e xhci-hcd

With an analogous way, you can proceed for displaying and the rest of
the xhci trace events.