[libhid-discuss] Cannot claim interface 0

Mark S. Townsley mstownsley at gmail.com
Fri Sep 29 01:09:50 UTC 2006


Yes I can follow the code in hid_interrupt_write().  But what does that
mean?
Does that mean libhid and libusb cannot be used to talk to my device?
It looks like I cannot set/get report (for write() and read()).  But what
does that mean?
Am I missing a step in the setup so report descriptors were not made
available?

On 9/28/06, Charles Lepple <clepple at ghz.cc> wrote:
>
> On Sep 28, 2006, at 8:09 PM, Mark S. Townsley wrote:
>
> > More info....
> >
> >
> > Before I go into all the libhid stuff, I actually called libusb
> > stuff, specifically
> > to usb_detach_kernel_driver_np().
>
> If you are calling libusb functions directly, you should be able to
> follow the code in hid_interrupt_write.
>
> > Since seeing the "could not detach from kernel errors", I comment
> > out the code,
> > rmmod the hid driver, and now interrupt_write()/read() returns this
> > error:
> >
> >   No error hid_interrupt_write 1 failed with return code 21
> >
> >
> > I have  hid_set_debug(10);
> >
> > What does return code 21 means?
>
> Return codes are enumerated here:
>
> http://www.ghz.cc/~clepple/libhid/doc/html/hid_8h.html#a64
>
> Check the source for hid_interrupt_write:
>
> http://www.ghz.cc/~clepple/libhid/doc/html/hid__exchange_8c-
> source.html#l00380
>
> --
> Charles Lepple
> clepple at ghz.cc
>
>
>
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