Hi

I have created a USB Class driver using the DDK and have come across a strange issue.

a) Plug device in.
b) Start driver - 
     - all the interfaces, endpoints are detected and opened OK.
     - set interface is called to select an alternate interface.
c) Threads are started that perform the USB IO when the application needs it.

Later, from within the other threads, usbd_io is called to write to a bulk out pipe. The first two calls succeed, but 
the third never returns (Timeout is infinity). A return URB (On the bulk in pipe) never receives any data.

Scenario 2

a) Start driver
b) Plug in device
  - as before, all USB config is setup and configured OK.
c) Application threads are started.
   - USBD_IO transmits OK.
   - USBD_IO receives data on the bulk in pipe.

I am baffled as why it should work in scenario 2, but not scenario 1. 
The device works fine under Linux, and I can't see the Linux driver doing anything particularly different.

I'd prefer scenario #1 to work. 

There's no other USB driver running, just the stack. 

Could this be a device issue? Or could it be some sort of startup/timing issue that's causing this problem?