VideoPortDoDma - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
// video.h

VIDEOPORT_DEPRECATED VIDEOPORT_API PDMA VideoPortDoDma(
  [in] IN PVOID     HwDeviceExtension,
  [in] IN PDMA      pDma,
  [in] IN DMA_FLAGS DmaFlags
);
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (nf-video-videoportdodma)

VideoPortDoDma function

Description

The VideoPortDoDma function is obsolete in Windows 2000 and later.

VideoPortDoDma causes the miniport driver's HwVidStartDma function to be called.

Parameters

HwDeviceExtension [in]

Pointer to the miniport driver's device extension.

pDma [in]

Specifies a non-NULL DMA handle. This handle was obtained from a prior call to VideoPortDoDma or from the OutputBuffer member of the VIDEO_REQUEST_PACKET returned by VideoPortLockPages.

DmaFlags [in]

Specifies the action to be performed. This member can be one of the following values:

Value Meaning
VideoPortKeepPagesLockedVideoPortDmaInitOnly If possible, the video port driver should keep the memory locked for subsequent DMA operation(s).
VideoPortUnlockAfterDma The video port driver should unlock the memory after the DMA operation is performed.

Return value

VideoPortDoDma always returns NULL.

Remarks

See Bus-Master DMA in Video Miniport Drivers for information about packet-based and common-buffer DMA transfers.

See also

VIDEO_REQUEST_PACKET

VideoPortLockPages

View the official Windows Driver Kit DDI reference

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