I do a IOUSBDevice::SetConfiguration(1) to get the second interface
(because the parameter is an index, not a value -- important safety
tip), but then calls to IOUSBDevice::FindNextInterface() fail to
find the last interface.
Are you totally sure of that? I'm expecting, and looking in the
source backs this up, that the parameter to SetConfiguration is the
configuration value, not an index.
There can be a great deal of confusion between the config index and
the config value, so to be clear:
The configuration descriptors are arranged as zero based array, they
are retrieved by index in a GET_DESCRIPTOR request, the indicies
would be 0,1 in your case.
The configuration value is one field of the configuration descriptor,
the spec either implies or requires (I'm not sure which) that this
value be a one based number, so it'd be 1,2 in your case. The
configuration value is what is passed in a SET_CONFIGURATION request
to specify the configuration.
The confusion comes because the index and value are offset by one and
both have to be used at various points. Note: zero is not a valid
configuration value, the spec specifically states a
SET_CONFIGURATION(0) is equivalent to unconfiguring a device. Its not
uncommon for single configuration devices to, incorrectly, specify
zero as the configuration value. Once you get to multiple
configuration devices this error really causes problems.
The series of commands your device should be getting to set the
second configuration is:
GET_DESCRIPTOR(config, 1)
SET_CONFIGURATION(2)
The note in the log says:
42.260 [5] foobar[0x1800200]::SetConfiguration to 1
Which is using a configuration value of 1, which should be the first
configuration as you're finding out. Its also what you specified in
the SetConfiguration.
So, are your configuration values correct (1,2)? and are you sending
the right value to SetConfiguration.
--
Barry Twycross
email@hidden
---
USB, it's not a Dyslexic BUS. (Thanks to TC.)
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Usb mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/usb/email@hidden
