drm: xlnx: zynqmp_disp: Skip the modeset for same fb

Since the async update creates a separate atomic mode set, there can be
back to back atomic modeset with same fb. If the mode set is applied
twice, it ends up submitting 2 dma transactions, and it results in
jitter. This fixes it by adding the check in plane atomic update,
and using plane mode set in async update.

Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Tested-by: Preetesh Parekh <preetesh.parekh@xilinx.com>

Author: xlnx-hyunkwon

drivers/gpu/drm/xlnx/zynqmp_disp.c

@@ -2676,6 +2676,9 @@ zynqmp_disp_plane_atomic_update(struct drm_plane *plane,
 	if (!plane->state->crtc || !plane->state->fb)
 		return;
 
+	if (plane->state->fb == old_state->fb)
+		return;
+
 	if (old_state->fb &&
 	    old_state->fb->format->format != plane->state->fb->format->format)
 		zynqmp_disp_plane_disable(plane);
@@ -2712,12 +2715,15 @@ static void
 zynqmp_disp_plane_atomic_async_update(struct drm_plane *plane,
 				      struct drm_plane_state *new_state)
 {
-	struct drm_plane_state *old_state =
-		drm_atomic_get_old_plane_state(new_state->state, plane);
+	int ret;
 
 	if (plane->state->fb == new_state->fb)
 		return;
 
+	if (plane->state->fb &&
+	    plane->state->fb->format->format != new_state->fb->format->format)
+		zynqmp_disp_plane_disable(plane);
+
 	 /* Update the current state with new configurations */
 	drm_atomic_set_fb_for_plane(plane->state, new_state->fb);
 	plane->state->crtc = new_state->crtc;
@@ -2731,7 +2737,19 @@ zynqmp_disp_plane_atomic_async_update(struct drm_plane *plane,
 	plane->state->src_h = new_state->src_h;
 	plane->state->state = new_state->state;
 
-	zynqmp_disp_plane_atomic_update(plane, old_state);
+	ret = zynqmp_disp_plane_mode_set(plane, plane->state->fb,
+					 plane->state->crtc_x,
+					 plane->state->crtc_y,
+					 plane->state->crtc_w,
+					 plane->state->crtc_h,
+					 plane->state->src_x >> 16,
+					 plane->state->src_y >> 16,
+					 plane->state->src_w >> 16,
+					 plane->state->src_h >> 16);
+	if (ret)
+		return;
+
+	zynqmp_disp_plane_enable(plane);
 }
 
 static const struct drm_plane_helper_funcs zynqmp_disp_plane_helper_funcs = {