PFREE_DMA_ENGINE callback function (hdaudio.h)

Article
10/21/2021

The FreeDmaEngine routine frees a DMA engine that was previously allocated by a call to AllocateCaptureDmaEngine or AllocateRenderDmaEngine.

The function pointer type for a FreeDmaEngine routine is defined as follows.

Syntax

PFREE_DMA_ENGINE PfreeDmaEngine;

NTSTATUS PfreeDmaEngine(
  [in] PVOID _context,
  [in] HANDLE Handle
)
{...}

Parameters

[in] _context

Specifies the context value from the Context member of the HDAUDIO_BUS_INTERFACE, the HDAUDIO_BUS_INTERFACE_V2 or HDAUDIO_BUS_INTERFACE_BDL structure.

[in] Handle

Handle identifying the DMA engine. This handle value was obtained from a previous call to AllocateCaptureDmaEngine or AllocateRenderDmaEngine.

Return value

FreeDmaEngine returns STATUS_SUCCESS if the call succeeds in freeing the DMA engine. Otherwise, the routine returns an appropriate error code. The following table shows some of the possible return status codes.

Return code	Description
STATUS_INVALID_HANDLE	Indicates that the handle parameter value is invalid.
STATUS_INVALID_DEVICE_REQUEST	Indicates that the stream is not in the reset state or that a buffer is still allocated for the DMA engine.

Remarks

This routine frees a DMA engine that was previously reserved by a call to the AllocateCaptureDmaEngine or AllocateRenderDmaEngine routine.

This routine fails and returns error code STATUS_INVALID_DEVICE_REQUEST in either of the following circumstances:

Any previously allocated DMA buffer has not been freed (by calling FreeDmaBuffer or FreeContiguousDmaBuffer).
The stream is in a state other than reset.

An audio driver calls this routine to close the pin (and destroy the stream).

Requirements

Requirement	Value
Target Platform	Desktop
Header	hdaudio.h (include Hdaudio.h)
IRQL	<=DISPATCH_LEVEL