[sane-devel] Regarding libUSB API (configurations)

[René Kjellerup]

Hi' every one.

This mail is primarily directed to those
of you who's writing USB applications.

My question meight seem simple, however 
the solution does elude me.

In my log file it takes my scanner 80ms to
select the configuration

Quote from log:
[5 ms]  >>>  URB 4 going down  >>>
-- URB_FUNCTION_SELECT_CONFIGURATION:
  ConfigurationDescriptor = 0x812d7c78 (configure)
  ConfigurationDescriptor : bLength             = 9
  ConfigurationDescriptor : bDescriptorType     = 0x00000002
  ConfigurationDescriptor : wTotalLength        = 0x00000027
  ConfigurationDescriptor : bNumInterfaces      = 0x00000001
  ConfigurationDescriptor : bConfigurationValue = 0x00000001
  ConfigurationDescriptor : iConfiguration      = 0x00000000
  ConfigurationDescriptor : bmAttributes        = 0x000000c0
  ConfigurationDescriptor : MaxPower            = 0x00000000
  ConfigurationHandle     = 0x00000000
  Interface[0]: Length            = 76
  Interface[0]: InterfaceNumber   = 0
  Interface[0]: AlternateSetting  = 0
[85 ms] UsbSnoop - MyInternalIOCTLCompletion(ad282db0) : fido=00000000,
Irp=814469a0, Context=821c7208, IRQL=0
[85 ms]  <<<  URB 4 coming back  <<<
End quote.

Well that's what my log says, my question is:
How in the world do I make a program call
to do this?

That is, is there some API to make the
URB_FUNCTION_SELECT_CONFIGURATION call to the
USB device (my scanner in this case), or does
libusb do this when getting the device?

Kind regards
René Kjellerup
-- as life grows older, I gain experience.