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
| Requirement | Value |
|---|---|
| Minimum supported client | Available starting with Windows 2000. |
| Target Platform | Desktop |
| Header | wdm.h (include Wdm.h, Ntddk.h, Ntifs.h) |
| IRQL | DISPATCH_LEVEL |
| DDI compliance rules | IrqlDispatch(storport), IrqlDispatch(storport), IrqlDispatch(wdm) |