WdfDmaTransactionFreeResources function (wdfdmatransaction.h)
[Applies to KMDF only]
The WdfDmaTransactionFreeResources method releases DMA resources that the driver previously allocated by calling WdfDmaTransactionAllocateResources.
Syntax
void WdfDmaTransactionFreeResources(
[in] WDFDMATRANSACTION DmaTransaction
);
Parameters
[in] DmaTransaction
A handle to the DMA transaction object that the driver provided in a previous call to WdfDmaTransactionAllocateResources.
Return value
None
Remarks
WdfDmaTransactionFreeResources must be used with a DMA enabler that specifies a packet or system profile.
On operating systems earlier than Windows 8, WdfDmaTransactionFreeResources must be used with an enabler that specifies a single-packet DMA enabler. Starting with Windows 8, WdfDmaTransactionFreeResources can also be used with an enabler that specifies a system-mode DMA enabler.
When called with a scatter/gather DMA enabler, WdfDmaTransactionFreeResources causes a verifier bug check.
The driver's call to WdfDmaTransactionFreeResources may cause the framework to call EvtProgramDma or EvtReserveDma immediately.
For more information about system-mode DMA, see Supporting System-Mode DMA.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Universal |
| Minimum KMDF version | 1.11 |
| Header | wdfdmatransaction.h (include Wdf.h) |
| Library | Wdf01000.sys (see Framework Library Versioning.) |
| IRQL | <=DISPATCH_LEVEL |
| DDI compliance rules | DriverCreate(kmdf) |