[libhid-discuss] hid_interrupt_read error codes

[Lars Krueger]

Hi.

I have some problems with the return codes of hid_interrupt_read. If libhid has a problem sending the packet to the device, it returns the same error code as if it hit the timeout.


My main loop is this:

while( 1)
{
    ret = hid_interrupt_read( theHid, theEndPoint, thePacket, thePacketLen, 20);

    printf( "ret=%d\n", ret);
      
      if( ret == HID_RET_SUCCESS )
      {
        ... Process packet
      }
      else
      {
        ... Do idle stuff

      }
}

The output is:
ret=21
ret=21 
ret=21 

When I unplug the device:

USB error: error submitting URB: No such device
ret=21
USB error: error submitting URB: No such device
ret=21

Error 21 is HID_RET_FAIL_INT_READ, which is acceptable, bug a timeout is strictly not a read failure.

Do I make any mistake using hid_interrupt_read, or is this a bug in libhid that the URB submission error is reported on stderr, but not in the error code?

Any help appreciated.

PS: I use libhid to convert USB keyboard events to X11 events in order to make radical keymap changes. See usbhotkey.sf.net for details.
-- 
Lars Krueger
http://LarsKrueger.homestead.com/files
mailto:lars_e_krueger at gmx.de


Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! 
Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer