VideoPortFreeDeviceBase function

The VideoPortFreeDeviceBase function frees a range of bus-relative device I/O ports or memory addresses previously mapped into the system address space. It does this by calling VideoPortGetDeviceBase.

Syntax


VOID VideoPortFreeDeviceBase(
   PVOID HwDeviceExtension,
   PVOID MappedAddress
);

Parameters

HwDeviceExtension

Pointer to the miniport driver's device extension.

MappedAddress

Specifies the base address of the mapped range to be freed. This value must be the same as the value returned by a preceding call to VideoPortGetDeviceBase.

Return value

None

Remarks

VideoPortFreeDeviceBase must be called from the miniport driver's HwVidFindAdapter function if the miniport driver has already mapped an address range for an adapter it cannot support or does not use any longer.

When this occurs, the miniport driver also must release its claim on the corresponding hardware resources in the registry. To release all claims on resources for a particular adapter, call VideoPortVerifyAccessRanges or VideoPortGetAccessRanges with the NumAccessRanges parameter set to zero. To release claims on selected access ranges, do the following:

  1. Modify the access ranges array of claimed bus-relative ranges for the adapter by setting the appropriate elements' RangeLength(s) to zero. Leave the current specification as is in all elements on which the miniport driver will not release its claims.

  2. Call VideoPortVerifyAccessRanges with this modified AccessRanges array.

Requirements

Target platform

Desktop

Version

Available in Windows 2000 and later versions of the Windows operating systems.

Header

Video.h (include Video.h)

Library

Videoprt.lib

DLL

Videoprt.sys

IRQL

PASSIVE_LEVEL

See also

HwVidFindAdapter
VideoPortGetAccessRanges
VideoPortGetDeviceBase
VideoPortVerifyAccessRanges

 

 

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