Provide information: All connected USB devices are enumerated at boot time

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Hi there,

I am currently working on a problem that I need to know when all
connected USB devices are enumerated when the system starts up.

The problem is the following:
* After the kernel finished booting, some hardware testing is performed
* This hardware testing involves various USB devices (e.g.: USB memory
  stick, USB touch controllers, etc.)
* The problem is that some USB devices appear after the test program has started

I could add a delay before the test is started. However the test should
work on a broad range of platforms with different USB devices. Therefore
it is difficult to find an optimal timeout value.

The desired solution is to wait on the enumeration of the connected USB
devices and start the test program.

I found the following thread:
  http://thread.gmane.org/gmane.linux.kernel/825135

In concrete: http://article.gmane.org/gmane.linux.kernel/826216
,----
| From: Alan Stern <stern <at> rowland.harvard.edu>
| Subject: Re: Wait for console to become available, v3.2
| Newsgroups: gmane.linux.kernel.embedded, gmane.linux.kernel, gmane.linux.usb.general
| Date: 2009-04-22 21:24:18 GMT (6 years, 25 weeks, 4 hours and 54 minutes ago)
| On Wed, 22 Apr 2009, Alan Cox wrote:
| 
| > > 2.	All devices have been probed
| > > If we exit for reason 2, it means that no such device is present,
| > > and we go on to the do the appropriate thing for that device class.
| > 
| > USB has no notion of #2 really
| 
| That's true, it doesn't.  But it _does_ rather have a notion of "all 
| devices that were present at boot time have been probed".  That should 
| be good enough.
| 
| Alan Stern
`----

So my question is whether the "all devices that were present at boot time have been probed"
is already available in the current kernel sources.

If it is not yet available: Is drivers/usb/core/hub.c the correct
location to start the implementation of such a feature?

Thanks,
  Stefan.

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