Bug#583731: Bug Traced to Application Code

[David Brodrick <david@ozforecast.com.au>]

I traced the change of behaviour when changing kernel versions to a 
problem in the application itself.

One of the usb_control_msg calls was being made with data that the 
device did not understand, and so the device was not responding and 
usb_interrupt_read was returning an error status that the developer (not 
me :-) never checked.

It is kind of amazing it ever worked, but the response buffer contained 
valid data from a previous usb call, however the patches to the kernel 
changed the contents of the buffer which 'broke' the broken application.

I updated the application code to fix the arguments to the 
usb_control_msg call so that device responded correctly and to check the 
return status of all of the usb calls and the application has now been 
verified to work properly on 2.6.26-21lenny4, 2.6.26-22lenny1, 2.6.32-5, 
2.6.32-trunk and a 2.6.34 kernel.

Apologies for not having a much deeper dig into this at the start.