Re: [Libusb-win32-devel] usb_claim interface return error code -22

[Lee C. <elc...@gm...>]

On Tue, Mar 23, 2010 at 6:00 AM, Belisko Marek <mar...@gm...> wrote:
> On Tue, Mar 23, 2010 at 11:29 AM, Xiaofan Chen <xia...@gm...> wrote:
>> On Tue, Mar 23, 2010 at 6:11 PM, Belisko Marek <mar...@gm...> wrote:
>>> trying to find out why usb_claim_interface return value -22 ( I can't
>>> find proper docu about this).
>>> Could you give me some hints? Using latest driver.
>>>
>> #define EINVAL          22      /* Invalid argument */
>>
>> Did you call usb_set_configuration() before? What is the
>> output of testlibusb-win.exe?
>>
>> If possible, please also post the code snippets.
>
> No I don't call usb_set_configuration(). I use this code on linux and
> it works perfectly.
> I try to use it on windows and get this error.
>
> Code snippet:
> int lusb::open_usb()
> {
>    int ret_val = 0;
>
>    if (this->dev != NULL) {
>        this->dev_handle = usb_open(this->dev);
>        if (this->dev_handle != NULL) {
>            /* claim interface must be done before every
>             * write or read to interface
>             */
>            ret_val = usb_claim_interface(this->dev_handle, 0);
>
>            if (ret_val < 0) {
>                perror("usb_claim_interface");
>                ret_val = 0;
>            } else {
>                ret_val = 1;
>            }
>        }
>    }
>
>    return ret_val;
> }
>

usb_set_configuration is required on Windows.  It works fine in Linux
too even though it isn't required there.

Lee C.