NvMediaTensorCreateFromNvSciBuf()

Creates an NvMedia Tensor handle from an NvSciBuf created with the NvSciBuf API, after the required NvSciBuf attributes list is prepared.

Every hardware engine in an NVIDIA SoC can have a different alignment or stride constraints. Hence, sharing a buffer across various engines requires that buffer allocation satisfies the constraints of all of the engines that share the buffer. An engine whose constraints are not satisfied may fail to operate on the buffer. The allocation functions provided by the various NvMedia drivers only satisfy the constraints of the engines that are visible to them, and so cannot be used to allocate shared buffers.

NvSciBuf is a buffer allocation module that satisfies a common set of constraints that are compatible with all of the hardware engines. It thus can allocate buffers that are shareable across the hardware engines visible to various drivers.

This is a typical flow to allocate an NvSciBufObj, which can be mapped to an NvMediaTensor:

1. The application creates an NvSciBufAttrList.
2. The application queries NvMedia to fill the NvSciBufAttrList by passing a set of NvMediaTensor allocation attributes and an NvMediaType as input to NvMediaTensorFillNvSciBufAttrs().
3. The application may set any of the public NvSciBufAttribute values that NvMedia does not set.

   For more details on NvSciBuf concepts, terminology, and the API, see Buffer Allocation.

   The following NvSciBuf input attributes are set by NvMedia, and must not be set by the application:

   • NvSciBufGeneralAttrKey_Types
   • NvSciBufGeneralAttrKey_NeedCpuAccess
   • NvSciBufGeneralAttrKey_EnableCpuCache
   • NvSciBufTensorAttrKey_DataType
   • NvSciBufTensorAttrKey_NumDims
   • NvSciBufTensorAttrKey_SizePerDim
   • NvSciBufTensorAttrKey_AlignmentPerDim
   • NvSciBufTensorAttrKey_StridesPerDim
   • NvSciBufTensorAttrKey_PixelFormat
   • NvSciBufTensorAttrKey_BaseAddrAlign
   The following attributes are not set by NvMedia and must be set by the application:

   • NvSciBufGeneralAttrKey_RequiredPerm
4. If the same NvSciBufObj object has to be shared with other user mode drivers (UMDs), the application can get the corresponding NvSciBufAttrList from the respective UMDs.
5. The application asks NvSciBuf to reconcile all of the filled NvSciBufAttrList objects, then allocates an NvSciBuf object.
6. The application queries NvMedia to create an NvMediaTensor from the allocated NvSciBuf object by calling NvMediaTensorCreateFromNvSciBuf().
7. The NvMediaTensor can be passed as input and output to any of the NvMedia API functions that accept an NvMediaTensor as a parameter.