DXGKDDI_DPI2CIOTRANSMISSION callback function (dispmprt.h)
The DXGKDDI_DPI2CIOTRANSMISSION callback performs DP I2C over AUX read/write operations on devices directly attached on GPU.
Syntax
DXGKDDI_DPI2CIOTRANSMISSION DxgkddiDpi2ciotransmission;
NTSTATUS DxgkddiDpi2ciotransmission(
HANDLE Context,
PDXGKARG_DPI2CIOTRANSMISSION pArgs
)
{...}
Parameters
Context
Context pointer provided when querying the interface.
pArgs
Pointer to a DXGKARG_DPI2CIOTRANSMISSION structure.
Return value
DXGKDDI_DPI2CIOTRANSMISSION returns STATUS_SUCCESS if it succeeds; otherwise it returns an error code such as one of the following:
| Error Code | Meaning |
|---|---|
| STATUS_DRIVER_INTERNAL_ERROR | An internal software error occurred. |
| STATUS_ACCESS_DENIED | The request is not supported. For Windows 10 version 2004, only I2C over AUX read is supported. |
| STATUS_BUFFER_TOO_SMALL | The buffer is too small for the operation. |
| STATUS_DEVICE_HARDWARE_ERROR | A hardware error occurred. |
| STATUS_DEVICE_POWERED_OFF | The device is powered off. |
| STATUS_DEVICE_NOT_CONNECTED | The device is not connected. |
| STATUS_DEVICE_PROTOCOL_ERROR | An error occurred at the I2C over AUX protocol level. The driver can use DPNativeError to encode more details about the error. |
Remarks
This DDI call is used to perform DP I2C over AUX read/write on devices directly attached on GPU.
For I2C, the maximum size of Data buffer in the DXGKARG_DPI2CIOTRANSMISSION structure pointed to by pArgs is 128 bytes. Combining a write operation before a read operation in a single bus transaction/cycle is supported for MCCS and other protocols. The Data buffer is of size BufferSizeSupplied, which should be greater than or equal to the larger value of BytesToWrite and BytesToRead.
Offset is the address for IO within the device. When EDDCMode is set, there are E-DDC devices at I2CAddress (0xA0 for EDID, 0xA4 for DisplayID). The driver should write SegmentPointer to I2C address 0x60, WordOffset to I2CAddress and then carry out the IO operation. For all other I2C devices, the driver should write bytes of Offset according to OffsetSizeInBytes.
In case of failure, the driver should return BytesWritten and BytesRead as accurately as possible.
For Windows 10 version 2004, the write operation is only allowed for MCCS I2C address of 0x6E. All other operations will be blocked until a later OS release when access control is added.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 10, version 2004 |
| Header | dispmprt.h |