[PATCH] drm/doc: Document legacy_cursor_update better

[Daniel Vetter]

It's the horror and shouldn't be used. Realized we're not clear on
this in a discussion with Rob about what msm is doing to better
support async commits.

Cc: Rob Clark <robdclark at gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
---
 include/drm/drm_atomic.h | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index d07c851d255b..413fd0ca56a8 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -308,7 +308,6 @@ struct __drm_private_objs_state {
  * struct drm_atomic_state - the global state object for atomic updates
  * @ref: count of all references to this state (will not be freed until zero)
  * @dev: parent DRM device
- * @legacy_cursor_update: hint to enforce legacy cursor IOCTL semantics
  * @async_update: hint for asynchronous plane update
  * @planes: pointer to array of structures with per-plane data
  * @crtcs: pointer to array of CRTC pointers
@@ -336,6 +335,17 @@ struct drm_atomic_state {
 	 * drm_atomic_crtc_needs_modeset().
 	 */
 	bool allow_modeset : 1;
+	/**
+	 * @legacy_cursor_update:
+	 *
+	 * Hint to enforce legacy cursor IOCTL semantics.
+	 *
+	 * WARNING: This is thoroughly broken and pretty much impossible to
+	 * implement correctly. Drivers must ignore this and should instead
+	 * implement &drm_plane_helper_funcs.atomic_async_check and
+	 * &drm_plane_helper_funcs.atomic_async_commit hooks. New users of this
+	 * flag are not allowed.
+	 */
 	bool legacy_cursor_update : 1;
 	bool async_update : 1;
 	/**
-- 
2.28.0