In  issue 820313 , we check the flush function in VEA unittest. But currently s5p-mfc encoder doesn't support flush correctly. We should implement the flush and remove the boards from the blacklist of flush at:

chromiumos/src/third_party/autotest/files/client/site_tests/video_VideoEncodeAccelerator/video_VideoEncodeAccelerator.py "has_broken_flush" method.