sun4i_rgb_init() can fail, which results in TCON failing to bind.
In this case we need to do cleanup, specificly unregistering the
dotclock, which is regmap based, and the regmap is registered as
part of the sun4i_tcon_bind().

Failing to do so results in a NULL pointer reference when the CCF
tries to turn off unused clocks.

Fixes: 29e57fab ("drm: sun4i: Add RGB output")
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

Our code currently defers our probe on any error, even if we were not
expecting to have one at all.

Make sure we return -EPROBE_DEFER only when we were supposed to have a
panel, but it's not probed yet.

Also fix a typo while we're at it.

Fixes: 29e57fab ("drm: sun4i: Add RGB output")
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

One of the A10 display pipeline possible output is an RGB interface to
drive LCD panels directly. This is done through the first channel of the
TCON that will output our video signals directly.
Reviewed-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

The Allwinner A10 and subsequent SoCs share the same display pipeline, with
variations in the number of controllers (1 or 2), or the presence or not of
some output (HDMI, TV, VGA) or not.

Add a driver with a limited set of features for now, and we will hopefully
support all of them eventually
Reviewed-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>