libusb interface already claimed

11
votes

I'm writing a device driver for a usb device using libusb. When I attempt to claim the device I get the error code LIBUSB_ERROR_BUSY (-6). According to the documentation that means that the device has already been claimed (link).

How do I find out which driver/program has claimed the device and more importantly, how can I, myself, claim the device once it's claimed.

Code snippet:

r = libusb_claim_interface(handle[0], 0);
if (r < 0) {
    fprintf(stderr, "libusb_claim_interface error %d\n", r);
    goto out_release;
}
printf("claimed interface\n");

Output:

libusb_claim_interface error -6
3
linuxusbdriverlibusb
I found this post looking for "How do I find out which driver/program has claimed the device", and so I wanted to link this question: Is there a way to figure out what is using a Linux kernel module?, which I think is relevant, because it says that it is not possible to see which programs claim a driver/module. - sdaau

3 Answers

17
votes

Do you call libusb_detach_kernel_driver() before libusb_claim_interface()? This may be necessary.

4
votes

The issue is most likely that interface is claimed by another Linux driver. call libusb_detach_kernel_driver() and specify the interface number and then you should be able to connect it.

0
votes

Did you call libusb_set_configuration() before libusb_claim_interface()?

This must be called even if there is only one configuration in the descriptor.