learning libusb 1.0 on a Phidgets SBC

[bob 295]

I've been plugging along up the USB and libusb learning curve using my 
Phidgets SBC as the toy.    This is all part of my open source project 
documented here:

http://www.icanprogram.com/opndrs/phidgets

I recently modified some libusb supplied sample code which does async I/O on 
an interrupt endpoint ... which is exactly what I need for the Phidgets SBC 
integrated 8/8/8 Interface Kit.

If I display the endpoint parameters associated with this USB endpoint it 
tells me that it will poll out at 8ms intervals.

However, when I introduce the poll() call as per this code snip:

http://www.icanprogram.com/opndrs/phidgets/2012Mar21.html

I see the poll delay being 7ms.    The period between my interrupt callbacks 
is still the expected 8ms.

The other curious thing is that my poll call returns with the POLLOUT bit set 
rather than the POLLIN bit I would have expected.    My Linux resources says 
that POLLOUT is "Writing now will not block".

Anyone have any thoughts?

Thanks in advance for your help.

bob
PS.
If anyone is interested in helping out with this little project,  by all means 
contact me offlist.   
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