libftdi Archives

Subject: Re: Any reason to call usb_set_configuration()

From: Xiaofan Chen <xiaofanc@xxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Cc: Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>, "Richard A. Smith" <richard@xxxxxxxxxx>
Date: Mon, 27 Jul 2009 20:06:35 +0800
On Mon, Jul 27, 2009 at 5:47 PM, Uwe
Bonnes<bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Is there perhaps an API to find out if setting the configuration is needed?
>
> Perhaps we can make the code dependant on that?
>

If libftdi switches to libusb 1.0 (it should be trival to switch to the
synchronous API of libusb 1.0), then you can use this
API function: libusb_get_configuration. You check if the
configuration is valid (typically 1), then you can skip
libusb_set_configuration(). If it is zero, then you
call  libusb_set_configuration().
http://libusb.sourceforge.net/api-1.0/group__dev.html

There are other advantages to switch to libusb 1.0 since
it supports asynchronous transfer. Currently it is only
working under Linux and Mac OS X.

For libusb 0.1, there is no direct API function to do this.
But you can probably do similar things.


-- 
Xiaofan http://mcuee.blogspot.com

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