Hi,
Can the dmafd be mapped to an EGLImage? If yes, you can call NvEGLImageFromFd() to get EGLImage of NvBuffer, and copy EGLImage of dmafd to EGLImage of NvBuffer.
This sample may help:
Trying to process with OpenGL an EGLImage created from a dmabuf_fd - #9 by DaneLLL