Difference Between UserLand and PlugInLand ?
Difference Between UserLand and PlugInLand ?
- Subject: Difference Between UserLand and PlugInLand ?
- From: Andy <email@hidden>
- Date: Sat, 14 Sep 2002 07:59:20 +0100
I have made a USB class that is basically a cut down version of the
code supplied by Apple in the Core-Audio SampleUSBDriver.
I have a command line test tool, using that code which simply polls a
bulk-in endpoint by doing async reads which are fired off again in the
completion callback.
This works fine, again and again, no problem.
btw. The device is continually pumping out MIDI active sensing bytes on
that endpoint or other MIDI messages if the user plays on the device.
However, when I put the exact same code into a MIDI Driver plug-in, it
works the first time the driver is loaded. But when the driver is
unloaded (all MIDI apps are quit) and then loaded again (another MIDI
app is run), the device times-out during configuration.
My trace/profiling output shows that all functions are called correctly
in the correct order, and that the class and MIDI driver
constructs/destructs apparently correctly with no errors.
Question:
Is there something I need to know about "MIDI driver land" being
different to other "user-land" spaces ?
Why would my USB code work in an ordinary application or command line
tool, but not in a MIDI Driver plugin ?
It looks like possibly the device is being left in a bad state when the
driver unloads ...
please, any possible clues, no matter how wild, would be appreciated ...
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