[Libusb-devel] claim interface fails when claimed by usbhid driver

[Brian N. <br...@tw...>]

Still having the same issues, here's a little more detail:

I'm running a recent Linux 2.6 kernel.  I have a HID device, shows up as 
a joystick (which it should).  I need to send a short two-byte control 
message to the device for configuration.

The problem I'm having is the usb_claim_interface call fails because 
it's already claimed by the usbhid driver.  I can disconnect it from the 
driver and the code works fine, but that's not what I want to do, 
because I want to maintain the joystick functionality that I already have.

I've attached my code and the output from it below.  Is this going to be 
possible?  Do I need to investigate other methods of communicating with 
the device, like hiddev or perhaps something on an even lower level?  I 
haven't done a ton of research, but I understand it might be possible to 
write to the device directly thorough the /proc/bus/usb/XXX/YYY file?

This process works fine under Windows, so I'm not sure where to go from 
here under Linux.  Thanks for any suggestions that anyone can offer.

-Brian

Program output (as root):

usb_set_debug: Setting debugging level to 8 (on)
usb_os_find_busses: Found 004
usb_os_find_busses: Found 003
usb_os_find_busses: Found 002
usb_os_find_busses: Found 001
usb_os_find_busses: Skipping non bus directory devices
usb_os_find_devices: Found 001 on 004
usb_os_find_devices: Found 001 on 003
usb_os_find_devices: Found 001 on 002
usb_os_find_devices: Found 002 on 001
skipped 1 class/vendor specific interface descriptors
usb_os_find_devices: Found 001 on 001
Check that you have permissions to write to 001/002 and, if you don't, 
that you set up hotplug (http://linux-hotplug.sourceforge.net/) correctly.
USB error: could not claim interface 0: Device or resource busy
USB error: error sending control message: Device or resource busy
usb_claim_interface error: could not claim interface 0: Device or 
resource busy
msg return: -16 | error sending control message: Device or resource busy

The code:

#include <usb.h>

int main(void)
{
  struct usb_bus *busses;
  struct usb_bus *bus;
  struct usb_device *dev;
  usb_dev_handle *usb_handle;

  int ret;
  unsigned char command[2] = {0xCC, 0x03};

  usb_init();
  usb_set_debug(8);
  usb_find_busses();
  usb_find_devices();

  busses = usb_get_busses();

  for (bus = busses; bus; bus = bus->next)
  {
      for (dev = bus->devices; dev; dev = dev->next)
      {
          if (dev->descriptor.idVendor == 0xFAFA)
          {
              usb_handle = usb_open(dev);
              if(usb_handle)
              {
                  if (usb_set_configuration(usb_handle, 
dev->config->bConfigurationValue))
                  {
                      printf("usb_set_configuration error: %s\n", 
usb_strerror());
                  }

                  usb_set_altinterface(usb_handle, 0);

                  if (usb_claim_interface(usb_handle, 0) < 0)
                  {
                      printf("usb_claim_interface error: %s\n", 
usb_strerror());
                  }

                  ret = usb_control_msg(usb_handle,
                          0x21,    // Set_Report request (page 52 HID Spec)
                          0x09,    // SET_REPORT (Top Remarks page 51)
                          0x200,    // (Bottom Remarks section page 51)
                          0x00,    // Interface 0
                          command,    // Buffer for characters to transmit
                          0x02,    // Size of message
                          10);     // Milliseconds of timeout

                  printf("msg return: %d | %s\n", ret, ret < 0 ? 
usb_strerror() : "<no error>");

                  usb_close(usb_handle);
              }
              else
              {
                  printf("Error opening device.\n");
              }
          }
      }
  }
}