drm/sun4i: engine: Add a custom crtc atomic_check

We have some restrictions on what the planes and CRTC can provide that are
tied to only one generation of display engines.

For example, on the first generation, we can only have one YUV plane or one
plane that uses the frontend output.

Let's allow our engines to provide an atomic_check callback to validate the
current configuration.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/e5f5f144e5c20d348cdb29933ae876c105bec017.1516613040.git-series.maxime.ripard@free-electrons.com

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sun4i/sunxi_engine.h b/drivers/gpu/drm/sun4i/sunxi_engine.h
index b374e07..b819d4f 100644
--- a/drivers/gpu/drm/sun4i/sunxi_engine.h
+++ b/drivers/gpu/drm/sun4i/sunxi_engine.h
@@ -23,6 +23,23 @@ struct sunxi_engine;
  */
 struct sunxi_engine_ops {
 	/**
+	 * @atomic_check:
+	 *
+	 * This callback allows to validate plane-update related CRTC
+	 * constraints specific to engines. This is mirroring the
+	 * &drm_crtc_helper_funcs.atomic_check callback, so any
+	 * documentation there applies.
+	 *
+	 * This function is optional.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success or a negative error code.
+	 */
+	int (*atomic_check)(struct sunxi_engine *engine,
+			    struct drm_crtc_state *state);
+
+	/**
 	 * @commit:
 	 *
 	 * This callback will trigger the hardware switch to commit