drm/sti: remove use of drm_debugfs functions as return values

Since commit 987d65d01356 (drm: debugfs: make
drm_debugfs_create_files() never fail), drm_debugfs_create_files() never
fails, and should return void. This change therefore removes it uses as
a return value in various functions across drm/sti.

With these changes, the affected functions have been changed to use a void
return value.

v2: convert sti_mixer_debugfs_init() and sti_compositor_debugfs_init()
to return void too. Also have sti_drm_dbg_init() to return 0 to avoid
build issues.

References: https://lists.freedesktop.org/archives/dri-devel/2020-February/257183.html
Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310133121.27913-10-wambui.karugax@gmail.com

gpu: drm: sti: Adopt SPDX identifiers

Add SPDX identifiers to files under sti directory

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Vincent Abriou <vincent.abriou@st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171206112947.9569-2-benjamin.gaignard@st.com

drm: sti: use late_register and early_unregister callbacks

Make sti driver use register callback to move debugfs
initialization out of sub-components creation.
This will allow to convert driver .load() to
drm_dev_alloc() and drm_dev_register().

sti_compositor bring up 2 crtc but only one debugfs init is
needed so use drm_crtc_index to do it on the first one.
This can't be done in sti_drv because only sti_compositor have
access to the devices.
It is almost the same for sti_encoder which handle multiple
encoder while one only debugfs entry is needed so add a boolean
to avoid multiple debugfs initialization

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1466514580-15194-3-git-send-email-benjamin.gaignard@linaro.org

drm/sti: add debugfs entries for VID plane

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

drm/sti: atomic crtc/plane update

Better fit STI hardware structure.
Planes are no more responsible of updating mixer information such
as z-order and status. It is now up to the CRTC atomic flush to
do it. Plane actions (enable or disable) are performed atomically.
Disabling of a plane is synchronize with the vsync event.

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

drm/sti: code clean up

Purpose is to simplify the STI driver:
- remove layer structure
- consider video subdev as part of the compositor (like mixer subdev)
- remove useless STI_VID0 and STI_VID1 enum

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

drm: sti: add VID layer

VIDeo plug are one of the compositor input sub-devices.
VID are dedicated to video inputs like YUV plans.

Like GDP, VID are part of Compositor hardware block
and use sti_layer structure to provide an abstraction for
Compositor calls.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>