I am trying to add a few properties to an IOUSBHostDevice but the SetProperties is returning kIOReturnUnsupported. The reason I am trying to modify the IOUSBHostDevice's properties is so we can support a MacBook Air SuperDrive when it is attached to our docking station devices. The MacBook Air SuperDrive needs a high powered port to run and this driver will help the OS realize that our dock can support it. I see that the documentation for SetProperties says: The default implementation of this method returns kIOReturnUnsupported. You can override this method and use it to modify the set of properties and values as needed. The changes you make apply only to the current service. Do I need to override IOUSBHostDevice? This is my current Start implementation (you can also see if in the Xcode project): kern_return_t IMPL(MyUserUSBHostDriver, Start) { kern_return_t ret = kIOReturnSuccess; OSDictionary * prop = NULL; OSDictionary * mergeProperties = NULL; bool success = true; os_log(OS_LOG_DEFAULT, "> %s", __FUNCTION__); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = Start(provider, SUPERDISPATCH); __Require(kIOReturnSuccess == ret, Exit); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ivars->host = OSDynamicCast(IOUSBHostDevice, provider); __Require_Action(NULL != ivars->host, Exit, ret = kIOReturnNoDevice); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = ivars->host->Open(this, 0, 0); __Require(kIOReturnSuccess == ret, Exit); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = CopyProperties(&prop); __Require(kIOReturnSuccess == ret, Exit); __Require_Action(NULL != prop, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); mergeProperties = OSDynamicCast(OSDictionary, prop->getObject("IOProviderMergeProperties")); mergeProperties->retain(); __Require_Action(NULL != mergeProperties, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); OSSafeReleaseNULL(prop); ret = ivars->host->CopyProperties(&prop); __Require(kIOReturnSuccess == ret, Exit); __Require_Action(NULL != prop, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); os_log(OS_LOG_DEFAULT, "%s : %s", "USB Product Name", ((OSString *) prop->getObject("USB Product Name"))->getCStringNoCopy()); os_log(OS_LOG_DEFAULT, "%s : %s", "USB Vendor Name", ((OSString *) prop->getObject("USB Vendor Name"))->getCStringNoCopy()); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); success = prop->merge(mergeProperties); __Require_Action(success, Exit, ret = kIOReturnError); os_log(OS_LOG_DEFAULT, "%s:%d", __FUNCTION__, __LINE__); ret = ivars->host->SetProperties(prop); // this is no working __Require(kIOReturnSuccess == ret, Exit); Exit: OSSafeReleaseNULL(mergeProperties); OSSafeReleaseNULL(prop); os_log(OS_LOG_DEFAULT, "err ref %d", kIOReturnUnsupported); os_log(OS_LOG_DEFAULT, "< %s %d", __FUNCTION__, ret); return ret; }