According to section 18.104.22.168 of the spec, on returning from UseEGLImage, "the pBuffer field of the pBufferHdr parameter shall be 0x0". That makes sense as an EGLimage is opaque, so the IL client can't access the data.
So, when the cmpt gets a call to Fill/EmptyThisBuffer, how does it get access to the EGLhandle and ultimately the pysical buffers? Looking at the buffer header structure, the only way to get to this data is through either pPlatformPrivate or pInputPortPrivate/pOutputPortPrivate fields.
From bug #3698, I guess the only field that the component is guaranteed to be able to use is the pInputPortPrivate/pOutputPortPrivate fields, is that correct?