Currently only linear formats are supported in sun4i-drm driver, but
SoCs like H6 supports AFBC variant of some of them in multiple cores
(GPU, VPU, DE3). Panfrost already implements AFBC compression and is
sometimes confused what should be default choice (linear, AFBC) if DRM
driver is not explicit about modifier support (MiniMyth2 distro with
MythTV app).

After some discussion with Daniel Stone on #panfrost IRC, it was decided
to make modifiers in sun4i-drm explicit, to avoid any kind of guessing,
not just in panfrost, but everywhere. In fact, long term idea is to make
modifier parameter in drm_universal_plane_init() mandatory (non NULL).
Signed-off-by: Piotr Oniszczuk <piotr.oniszczuk@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210605073534.3786194-1-jernej.skrabec@gmail.com