device filtering support

[Travis]

On 2/3/2012 7:44 AM, Pete Batard wrote:
>> is a bit absurd considering
>> the performance problems you already have,
>
> On the contrary, it eliminates performance issues due to enum, since 
> after that one time complete enum, where NO libusbx app is yet able to 
> access a device, enum only needs to be concerned about devices plugged 
> in or removed.

What happens if there is only one app?  Then you have not solved 
anything.  In-fact, you have added a bunch of overhead to the most 
common scenario.  This is a crazy idea. I hope you are not actually 
considering this.

..And FYI,  libusb-win32, WInUSB and libusbK cache device and config 
descriptors fi you fetch them with the GetDescriptor api.

The best option is to only list devices that you can use, and get 
descriptors from the drivers you support (where they are already cached).

For HID there may be no other way, but at-least you would not be 
punishing every device on the system with descriptor request.


Regards,
Travis