Currently we take a reference on the underlying client buffer every time
we materialise a drm_fb from a view, and release it when the drm_fb is
destroyed. This means that we need to create and destroy a drm_fb every
time we want to use it, which is pathologically unperformant on some
platforms.
To start working towards being able to cache drm_fb, only take the
reference when we apply it to a plane state.
Signed-off-by: Daniel Stone <daniels@collabora.com>
267f6cc6a1