DMA_FLAGS - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
// video.h
typedef enum {
VideoPortUnlockAfterDma,
VideoPortKeepPagesLocked,
VideoPortDmaInitOnly
} DMA_FLAGS;
View the official Windows Driver Kit DDI referenceNo description available.
The DMA_FLAGS enumeration specifies flags for the VideoPortLockPages or VideoPortDoDma functions.
VideoPortUnlockAfterDmaTells the video port to unlock the pages after the miniport signals that the DMA is complete via the pDmaCompletionEvent in HwStartDma. Failure to set this event at DMA completion can cause the memory to be unlocked at random times. This flag is best used when one wants to do one DMA transfer that occurs infrequently. It allows locking, DMAing, and unlocking to be performed in the context of one IOCTL.
VideoPortKeepPagesLockedTells the video port to leave the pages locked if possible.
VideoPortDmaInitOnlyTells the video port to lock the pages but not call the miniport's HwStartDma routine. This flag isn't applicable to VideoPortDoDma.