What does HRESULT 0x80660002 (E_HDAUDIO_EMPTY_CONNECTION_LIST) mean?

E_HDAUDIO_EMPTY_CONNECTION_LIST

The scope of E_HDAUDIO_EMPTY_CONNECTION_LIST is HD Audio widget connection-list parsing. An HD Audio widget that should expose routable connections reported an empty connection list. Keep 0x80660002 beside the returning method because a wrapper can replace this distinction with a generic subsystem message.

Locate the first rejecting layer

HD Audio codecs expose a graph of pins, converters, selectors, mixers, and processing widgets. Some widgets publish selectable connection lists, while others have fixed or implicit routes. Driver code must read the widget capability bits and type before requesting connection-list parameters, and it must treat a required-but-empty list differently from a widget that never supports such a list.

In the HD Audio codec graph, connection lists link widgets such as pins, selectors, mixers, converters, and processing nodes. An unexpected empty list means topology enumeration cannot establish a valid upstream or downstream route for that widget.

Misleading responses

E_HDAUDIO_CONNECTION_LIST_NOT_SUPPORTED means the widget does not advertise this parameter at all; EMPTY_CONNECTION_LIST means a list path was reached but no usable entries were present. Do not fabricate a connection to make endpoint construction continue; an invented route can connect the wrong converter or expose unsafe controls.

Evidence to preserve

• Codec vendor/device and subsystem IDs
• Function group, node ID, widget capabilities, and raw connection-list response
• Driver parser index and expected connection count
• Codec reset and power-state history

Controlled reproduction

Dump the raw codec verbs and widget capabilities for the exact node before creating logical endpoints. Compare them with the topology the driver builds, rather than substituting data from another codec revision with a similar marketing name.

1. Dump the codec topology directly before the function driver transforms it.
2. Compare cold boot, resume, and codec-reset results.
3. Check short-form versus long-form connection-list encoding and range entries.
4. Validate vendor firmware against the HD Audio specification and a known-good driver.

Technical references

• Microsoft: COM error codes for Input and graphics.
• Microsoft: PortCls interfaces and structures.
• Microsoft: Windows audio driver design guide.
• Microsoft: hdaudio.h header reference.
• Microsoft: SysVAD virtual audio driver sample.