drm/atomic: Let drivers decide which planes to async flip

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.

Create a new parameter for the atomic_async_check(), `bool flip`. This
parameter is used to distinguish when this function is being called from
a plane update from a full page flip.

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 <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Reviewed-by: Christopher Snowhill <[e-mail]>
Tested-by: Christopher Snowhill <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

drivers/gpu/drm/drm_atomic_helper.c

···
 		return -EBUSY;
 	}
 
-	ret = funcs->atomic_async_check(plane, state);
+	ret = funcs->atomic_async_check(plane, state, false);
 	if (ret != 0)
 		drm_dbg_atomic(dev,
 			       "[PLANE:%d:%s] driver async check failed\n",

drivers/gpu/drm/drm_atomic_uapi.c

···
  * Daniel Vetter <[e-mail]>
  */
 
-#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>
···
 		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)) {
···
 			break;
 		}
 
-		if (async_flip &&
-		    (plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY ||
-		     (prop != config->prop_fb_id &&
-		      prop != config->prop_in_fence_fd &&
-		      prop != config->prop_fb_damage_clips))) {
-			ret = drm_atomic_plane_get_property(plane, plane_state,
-							    prop, &old_val);
-			ret = drm_atomic_check_prop_changes(ret, old_val, prop_value, prop);
-			break;
+		if (async_flip) {
+			/* check if the prop does a nop change */
+			if ((prop != config->prop_fb_id &&
+			     prop != config->prop_in_fence_fd &&
+			     prop != config->prop_fb_damage_clips)) {
+				ret = drm_atomic_plane_get_property(plane, plane_state,
+								    prop, &old_val);
+				ret = drm_atomic_check_prop_changes(ret, old_val, prop_value, prop);
+			}
+
+			/* ask the driver if this non-primary plane is supported */
+			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, true);
+
+				if (ret) {
+					drm_dbg_atomic(prop->dev,
+						       "[PLANE:%d:%s] does not support async flips\n",
+						       obj->id, plane->name);
+					break;
+				}
+			}
 		}
 
 		ret = drm_atomic_plane_set_property(plane,

drivers/gpu/drm/loongson/lsdc_plane.c

···
 };
 
 static int lsdc_cursor_plane_atomic_async_check(struct drm_plane *plane,
-						struct drm_atomic_state *state)
+						struct drm_atomic_state *state,
+						bool flip)
 {
 	struct drm_plane_state *new_state;
 	struct drm_crtc_state *crtc_state;

drivers/gpu/drm/mediatek/mtk_plane.c

···
 }
 
 static int mtk_plane_atomic_async_check(struct drm_plane *plane,
-					struct drm_atomic_state *state)
+					struct drm_atomic_state *state, bool flip)
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);

drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c

···
 }
 
 static int mdp5_plane_atomic_async_check(struct drm_plane *plane,
-					 struct drm_atomic_state *state)
+					 struct drm_atomic_state *state, bool flip)
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

···
 }
 
 static int vop_plane_atomic_async_check(struct drm_plane *plane,
-					struct drm_atomic_state *state)
+					struct drm_atomic_state *state, bool flip)
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);

drivers/gpu/drm/tegra/dc.c

···
 	tegra_dc_writel(dc, value, DC_DISP_DISP_WIN_OPTIONS);
 }
 
-static int tegra_cursor_atomic_async_check(struct drm_plane *plane, struct drm_atomic_state *state)
+static int tegra_cursor_atomic_async_check(struct drm_plane *plane, struct drm_atomic_state *state,
+					   bool flip)
 {
 	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state, plane);
 	struct drm_crtc_state *crtc_state;

drivers/gpu/drm/vc4/vc4_plane.c

···
 }
 
 static int vc4_plane_atomic_async_check(struct drm_plane *plane,
-					struct drm_atomic_state *state)
+					struct drm_atomic_state *state, bool flip)
 {
 	struct vc4_dev *vc4 = to_vc4_dev(plane->dev);
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,

include/drm/drm_modeset_helper_vtables.h

···
 	 * given update can be committed asynchronously, that is, if it can
 	 * jump ahead of the state currently queued for update.
 	 *
+	 * This function is also used by drm_atomic_set_property() to determine
+	 * if the plane can be flipped in async. The flip flag is used to
+	 * distinguish if the function is used for just the plane state or for a
+	 * flip.
+	 *
 	 * RETURNS:
 	 *
 	 * Return 0 on success and any error returned indicates that the update
 	 * can not be applied in asynchronous manner.
 	 */
 	int (*atomic_async_check)(struct drm_plane *plane,
-				  struct drm_atomic_state *state);
+				  struct drm_atomic_state *state, bool flip);
 
 	/**
 	 * @atomic_async_update: