3 files changed, 47 insertions, 1 deletions

diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 2095917ff8c7..a0ea4ded3cb5 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -127,4 +127,41 @@ void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 #define drm_atomic_crtc_state_for_each_plane(plane, crtc_state) \
 	drm_for_each_plane_mask(plane, (crtc_state)->state->dev, (crtc_state)->plane_mask)
 
+/*
+ * drm_atomic_plane_disabling - check whether a plane is being disabled
+ * @plane: plane object
+ * @old_state: previous atomic state
+ *
+ * Checks the atomic state of a plane to determine whether it's being disabled
+ * or not. This also WARNs if it detects an invalid state (both CRTC and FB
+ * need to either both be NULL or both be non-NULL).
+ *
+ * RETURNS:
+ * True if the plane is being disabled, false otherwise.
+ */
+static inline bool
+drm_atomic_plane_disabling(struct drm_plane *plane,
+			   struct drm_plane_state *old_state)
+{
+	/*
+	 * When disabling a plane, CRTC and FB should always be NULL together.
+	 * Anything else should be considered a bug in the atomic core, so we
+	 * gently warn about it.
+	 */
+	WARN_ON((plane->state->crtc == NULL && plane->state->fb != NULL) ||
+		(plane->state->crtc != NULL && plane->state->fb == NULL));
+
+	/*
+	 * When using the transitional helpers, old_state may be NULL. If so,
+	 * we know nothing about the current state and have to assume that it
+	 * might be enabled.
+	 *
+	 * When using the atomic helpers, old_state won't be NULL. Therefore
+	 * this check assumes that either the driver will have reconstructed
+	 * the correct state in ->reset() or that the driver will have taken
+	 * appropriate measures to disable all planes.
+	 */
+	return (!old_state || old_state->crtc) && !plane->state->crtc;
+}
+
 #endif /* DRM_ATOMIC_HELPER_H_ */
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index e76828d81a8b..5810c027acdc 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -115,6 +115,7 @@ struct drm_crtc_helper_funcs {
  * @get_crtc: return CRTC that the encoder is currently attached to
  * @detect: connection status detection
  * @disable: disable encoder when not in use (overrides DPMS off)
+ * @atomic_check: check for validity of an atomic update
  *
  * The helper operations are called by the mid-layer CRTC helper.
  */
@@ -137,6 +138,11 @@ struct drm_encoder_helper_funcs {
 					    struct drm_connector *connector);
 	/* disable encoder when not in use - more explicit than dpms off */
 	void (*disable)(struct drm_encoder *encoder);
+
+	/* atomic helpers */
+	int (*atomic_check)(struct drm_encoder *encoder,
+			    struct drm_crtc_state *crtc_state,
+			    struct drm_connector_state *conn_state);
 };
 
 /**
diff --git a/include/drm/drm_plane_helper.h b/include/drm/drm_plane_helper.h
index a185392cafeb..31c11d36fae6 100644
--- a/include/drm/drm_plane_helper.h
+++ b/include/drm/drm_plane_helper.h
@@ -52,7 +52,8 @@ extern int drm_crtc_init(struct drm_device *dev,
  * @prepare_fb: prepare a framebuffer for use by the plane
  * @cleanup_fb: cleanup a framebuffer when it's no longer used by the plane
  * @atomic_check: check that a given atomic state is valid and can be applied
- * @atomic_update: apply an atomic state to the plane
+ * @atomic_update: apply an atomic state to the plane (mandatory)
+ * @atomic_disable: disable the plane
  *
  * The helper operations are called by the mid-layer CRTC helper.
  */
@@ -66,6 +67,8 @@ struct drm_plane_helper_funcs {
 			    struct drm_plane_state *state);
 	void (*atomic_update)(struct drm_plane *plane,
 			      struct drm_plane_state *old_state);
+	void (*atomic_disable)(struct drm_plane *plane,
+			       struct drm_plane_state *old_state);
 };
 
 static inline void drm_plane_helper_add(struct drm_plane *plane,