Defined in the Bluez bluetooth stack in hci.h is the following:
/* HCI Socket options */
#define HCI_DATA_DIR 1
#define HCI_FILTER 2
#define HCI_TIME_STAMP 3
I've only seen HCI_FILTER being used to set HCI event filters for the host. I have been unable to find any resources that explain what the other two options (HCI_DATA_DIR and HCI_TIME_STAMP) are used for and what is expected for option_value when calling setsockopt().
Is there any sort of documentation that goes over these details?