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The DxgkDdiQueryDeviceDescriptor function returns a descriptor for a child device of a display adapter or for an external device (typically a monitor) connected to a child device of a display adapter.
Syntax
DXGKDDI_QUERY_DEVICE_DESCRIPTOR DxgkddiQueryDeviceDescriptor;
NTSTATUS DxgkddiQueryDeviceDescriptor(
[in] IN_CONST_PVOID MiniportDeviceContext,
[in] IN_ULONG ChildUid,
[in, out] INOUT_PDXGK_DEVICE_DESCRIPTOR DeviceDescriptor
)
{...}
Parameters
[in] MiniportDeviceContext
A handle to a context block associated with a display adapter. The display miniport driver's DxgkDdiAddDevice function previously provided this handle to the DirectX graphics kernel subsystem.
[in] ChildUid
An integer that uniquely identifies the child device. The display miniport driver's DxgkDdiQueryChildRelations function previously provided this identifier to the display port driver.
[in, out] DeviceDescriptor
A pointer to a DXGK_DEVICE_DESCRIPTOR structure. The caller initializes the DescriptorLength and DescriptorBuffer members. If the child device has a type of TypeVideoOutput, the caller also initializes the DescriptorOffset member. On return, the caller-allocated buffer pointed to by the DescriptorBuffer member receives the descriptor.
Return value
DxgkDdiQueryDeviceDescriptor returns one of the following values:
| Return code | Description |
|---|---|
| STATUS_SUCCESS | The function successfully returned the device descriptor. |
| STATUS_GRAPHICS_CHILD_DESCRIPTOR_NOT_SUPPORTED | The (onboard) child device identified by ChildUid does not support a descriptor. |
| STATUS_MONITOR_NO_DESCRIPTOR | The child device identified by ChildUid is connected to a monitor that does not support an EDID descriptor. |
| STATUS_MONITOR_NO_MORE_DESCRIPTOR_DATA | The child device identified by ChildUid is connected to a monitor that does support an EDID descriptor, but the descriptor does not have the EDID extension block specified by the DescriptorOffset and DescriptorLengthmembers of DeviceDescriptor. |
Remarks
DxgkDdiQueryDeviceDescriptor must never write more than the number of bytes specified by DeviceDescriptor->DescriptorLength.
If the child device identified by ChildUid has a type of TypeVideoOutput, DxgkDdiQueryDeviceDescriptor returns a portion of the Extended Display Identification Data (EDID) for the monitor connected to the output. DeviceDescriptor->DescriptorOffset specifies the byte-offset into the EDID of the start of the data to be returned.
If the child device identified by ChildUid is not a video output, DxgkDdiQueryDeviceDescriptor returns a generic device descriptor; that is, it fills in the members of a DXGK_GENERIC_DESCRIPTOR structure.
The DxgkDdiQueryDeviceDescriptor function can be called several times for one child device. For a child device that has a connected monitor, the display port driver calls DxgkDdiQueryDeviceDescriptor during initialization to obtain the first 128-byte block of a monitor's EDID. Later the monitor class function driver (Monitor.sys) calls DxgkDdiQueryDeviceDescriptor to obtain selected portions (including the first 128-byte block) of that same monitor's EDID.
DxgkDdiQueryDeviceDescriptor should be made pageable.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows Vista |
| Target Platform | Desktop |
| Header | dispmprt.h |
| IRQL | PASSIVE_LEVEL |