PFREE_ADAPTER_CHANNEL callback function (wdm.h)

The FreeAdapterChannel routine releases the system DMA controller when a driver has completed all DMA operations necessary to satisfy the current IRP.

Syntax

PFREE_ADAPTER_CHANNEL PfreeAdapterChannel;

void PfreeAdapterChannel(
  [in] PDMA_ADAPTER DmaAdapter
)
{...}

Parameters

[in] DmaAdapter

Pointer to the DMA_ADAPTER structure returned by IoGetDmaAdapter that represents the bus-master adapter or DMA controller.

Return value

None

Remarks

FreeAdapterChannel is not a system routine that can be called directly by name. This routine is callable only by pointer from the address returned in a DMA_OPERATIONS structure. Drivers obtain the address of this routine by calling IoGetDmaAdapter.

After a driver has transferred all the data and called FlushAdapterBuffers, it calls FreeAdapterChannel to release the system DMA controller that was previously allocated with a call to AllocateAdapterChannel.

FreeAdapterChannel frees any map registers that were allocated by an earlier call to AllocateAdapterChannel. A driver calls this routine only if its AdapterControl routine returns KeepObject.

Requirements

See also

AllocateAdapterChannel

DMA_ADAPTER

DMA_OPERATIONS

FlushAdapterBuffers

FreeMapRegisters

IoGetDmaAdapter

MapTransfer