[PATCH v8 1/2] drm/atomic: Let drivers decide which planes to async flip

[André Almeida <andrealmeid@xxxxxxxxxx>]

Currently, DRM atomic uAPI allows only primary planes to be flipped
asynchronously. However, each driver might be able to perform async
flips in other different plane types. To enable drivers to set their own
restrictions on which type of plane they can or cannot flip, use the
existing atomic_async_check() from struct drm_plane_helper_funcs to
enhance this flexibility, thus allowing different plane types to be able
to do async flips as well.

In order to prevent regressions and such, we keep the current policy: we
skip the driver check for the primary plane, because it is always
allowed to do async flips on it.

Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 7609c798d73d..d888ee8f7a11 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -27,8 +27,9 @@
  * Daniel Vetter <daniel.vetter@xxxxxxxx>
  */
 
-#include <drm/drm_atomic_uapi.h>
 #include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_atomic_uapi.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_print.h>
 #include <drm/drm_drv.h>
@@ -1063,6 +1064,7 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
 		struct drm_plane *plane = obj_to_plane(obj);
 		struct drm_plane_state *plane_state;
 		struct drm_mode_config *config = &plane->dev->mode_config;
+		const struct drm_plane_helper_funcs *plane_funcs = plane->helper_private;
 
 		plane_state = drm_atomic_get_plane_state(state, plane);
 		if (IS_ERR(plane_state)) {
@@ -1080,11 +1082,20 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
 			break;
 		}
 
-		if (async_flip && plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY) {
-			drm_dbg_atomic(prop->dev,
-				       "[OBJECT:%d] Only primary planes can be changed during async flip\n",
-				       obj->id);
-			ret = -EINVAL;
+		if (async_flip) {
+			/* we always allow primary planes */
+			if (plane->type != DRM_PLANE_TYPE_PRIMARY) {
+				ret = -EINVAL;
+
+				if (plane_funcs && plane_funcs->atomic_async_check)
+					ret = plane_funcs->atomic_async_check(plane, state);
+
+				if (ret) {
+					drm_dbg_atomic(prop->dev,
+						       "[PLANE:%d] does not support async flips\n",
+							obj->id);
+				}
+			}
 			break;
 		}
 
-- 
2.45.2