![]() ![]() When the audio driver sends IOCTLs to the HFP driver, the driver uses the HFP FileObject and the DeviceObject for the HFP device. When the audio driver calls IoGetDeviceObjectPointer, the driver uses the symbolic link to get the HFP FileObject and the DeviceObject for the HFP device. When Windows calls the audio driver’s callback routine that was registered when the audio driver called IoRegisterPlugPlayNotification, Windows passes a symbolic link for the HFP interface, using DEVICE_INTERFACE_CHANGE_NOTIFICATION. Handling interface instancesįor each interface instance that is registered in the GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS class, the audio driver must use the following protocol for communication: ![]() The following sections outline the tasks that the audio driver can performs for each registered instance of a paired HFP device. ![]() ![]() However some alternate audio driver designs might find existing interfaces through other means.ĮventCategoryData is set to GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS.ĭriverObject is set to the audio driver’s DriverObject.ĬallbackRoutine is set to a routine in the audio driver that will receive the notifications. When the audio driver calls IoRegisterPlugPlayNotification, the call is made using the following parameters.ĮventCategory is set to EventCategoryDeviceInterfaceChange.ĮventCategoryFlags is typically set to PNPNOTIFY_DEVICE_INTERFACE_INCLUDE_EXISTING_INTERFACES in order to receive immediate notifications of existing interfaces. The audio driver calls IoRegisterPlugPlayNotification from within its AVStrMiniDevicePostStart driver routine (or from an equivalent Portcls routine) to register a callback to discover the currently installed HFP devices, and to be notified of new HFP devices. The audio driver uses device interface notifications to stay informed of all instances of the GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS interfaces. The HFP Device startup topic discusses what happens when a Bluetooth hands-free profile (HFP) device arrives in the audio system.įor each paired HFP device that arrives in the audio system, the Windows HFP driver registers a device interface in the GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS class. ![]()
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