Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All
Expand Minimize

Timers in Video Miniport Drivers

Any video miniport driver can have a HwVidTimer function at the discretion of the driver writer. A HwVidTimer function allows the miniport driver to time out operations or to monitor state changes over a coarser-grained interval than is possible by calling VideoPortStallExecution. HwVidTimer also does not prevent other system operations from occurring as VideoPortStallExecution does.

For example, a miniport driver for an adapter that emulates VGA functionality might have a HwVidTimer function that monitors the status of its adapter's "VGA" registers periodically so the driver can emulate VGA-style graphics.

After a call to VideoPortStartTimer, the video port driver calls HwVidTimer once every second until the video miniport driver calls VideoPortStopTimer. A video miniport driver can enable and disable calls to the HwVidTimer function repeatedly.

Note that a HwVidTimer function cannot disable calls to itself with VideoPortStopTimer. Another video miniport driver function must control the enabling or disabling of calls to a HwVidTimer function through the use of VideoPortStartTimer and VideoPortStopTimer.

 

 

Send comments about this topic to Microsoft

Show:
© 2015 Microsoft