drm/amd/display: Refine condition for cursor visibility

[why]
There's a special case where upper plane is not the main plane. If it owns
the cursor, it will be invisible in the majority of the screen.

[How]
The condition for disabling cursor is changed:
- check if upper viewport completely covers current. This was the
previous change that doesn't handle all scenarios with pipe splitting.
- if not, show the cursor only if it's not scaled or no upper pipe.
Reviewed-by: Aric Cyr <aric.cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -3177,21 +3177,40 @@ void dcn10_update_dchub(struct dce_hwseq *hws, struct dchub_init_data *dh_data)
 static bool dcn10_can_pipe_disable_cursor(struct pipe_ctx *pipe_ctx)
 {
 	struct pipe_ctx *test_pipe;
+	const struct scaler_data *scl_data = &pipe_ctx->plane_res.scl_data;
+	const struct rect *r1 = &scl_data->recout, *r2;
+	int r1_r = r1->x + r1->width, r1_b = r1->y + r1->height, r2_r, r2_b;
 	int cur_layer = pipe_ctx->plane_state->layer_index;
+	bool upper_pipe_exists = false;
+	struct fixed31_32 one = dc_fixpt_from_int(1);
 
 	/**
-	 * Disable the cursor if there's there's an upper layer active,
-	 * assume it's the one owning the cursor
+	 * Disable the cursor if there's another pipe above this with a
+	 * plane that contains this pipe's viewport to prevent double cursor
+	 * and incorrect scaling artifacts.
 	 */
 	for (test_pipe = pipe_ctx->top_pipe; test_pipe;
 	     test_pipe = test_pipe->top_pipe) {
 		if (!test_pipe->plane_state->visible)
 			continue;
 
-		if (test_pipe->plane_state->layer_index < cur_layer)
+		r2 = &test_pipe->plane_res.scl_data.recout;
+		r2_r = r2->x + r2->width;
+		r2_b = r2->y + r2->height;
+
+		if (r1->x >= r2->x && r1->y >= r2->y && r1_r <= r2_r && r1_b <= r2_b)
 			return true;
+
+		if (test_pipe->plane_state->layer_index < cur_layer)
+			upper_pipe_exists = true;
 	}
 
+	// if plane scaled, assume an upper plane can handle cursor if it exists.
+	if (upper_pipe_exists &&
+			(scl_data->ratios.horz.value != one.value ||
+			scl_data->ratios.vert.value != one.value))
+		return true;
+
 	return false;
 }
 

drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h

@@ -2636,6 +2636,7 @@ static inline bool dmub_rb_pop_front(struct dmub_rb *rb)
  */
 static inline void dmub_rb_flush_pending(const struct dmub_rb *rb)
 {
+	uint8_t buf[DMUB_RB_CMD_SIZE];
 	uint32_t rptr = rb->rptr;
 	uint32_t wptr = rb->wrpt;