dmabuf: Require valid fds for all planes
This seems to be what everyone does, so we should do it, too.
Previously it was assumed that an fd of -1 would mean reusing the previous fd with a different offset, but that seems to be uncommon.
This seems to be what everyone does, so we should do it, too.
Previously it was assumed that an fd of -1 would mean reusing the previous fd with a different offset, but that seems to be uncommon.