drm/amd/display: fix underflow in some two display subvp/non-subvp configs

[Why]
In two display configuration, switching between subvp and non-subvp
 may cause underflow because it moves an existing pipe between
 displays

[How]
Create helper function for applying pipe split flags
Apply pipe split flags prior to deciding on subvp
During subvp check, do not merge pipes, so it can retain previous
 pipe configuration
Add check for prev odm pipe in subvp check
For single display subvp case, use same odm policy for phantom pipes
 as main subvp pipe
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Samson Tam <samson.tam@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource.c

@@ -1815,9 +1815,47 @@ int dcn32_populate_dml_pipes_from_context(
 	struct pipe_ctx *pipe = NULL;
 	bool subvp_in_use = false;
 	struct dc_crtc_timing *timing;
+	int subvp_main_pipe_index = -1;
+	enum mall_stream_type mall_type;
+	bool single_display_subvp = false;
+	struct dc_stream_state *stream = NULL;
+	int num_subvp_main = 0;
+	int num_subvp_phantom = 0;
+	int num_subvp_none = 0;
 
 	dcn20_populate_dml_pipes_from_context(dc, context, pipes, fast_validate);
 
+	/* For single display subvp, look for subvp main so if we have phantom
+	 *  pipe, we can set odm policy to match main pipe
+	 */
+	for (i = 0; i < context->stream_count; i++) {
+		stream = context->streams[i];
+		mall_type = dc_state_get_stream_subvp_type(context, stream);
+		if (mall_type == SUBVP_MAIN)
+			num_subvp_main++;
+		else if (mall_type == SUBVP_PHANTOM)
+			num_subvp_phantom++;
+		else
+			num_subvp_none++;
+	}
+	if (num_subvp_main == 1 && num_subvp_phantom == 1 && num_subvp_none == 0)
+		single_display_subvp = true;
+
+	if (single_display_subvp) {
+		for (i = 0, pipe_cnt = 0; i < dc->res_pool->pipe_count; i++) {
+			pipe = &res_ctx->pipe_ctx[i];
+			if (!res_ctx->pipe_ctx[i].stream)
+				continue;
+
+			mall_type = dc_state_get_pipe_subvp_type(context, pipe);
+			if (mall_type == SUBVP_MAIN) {
+				if (resource_is_pipe_type(pipe, OTG_MASTER))
+					subvp_main_pipe_index = pipe_cnt;
+			}
+			pipe_cnt++;
+		}
+	}
+
 	for (i = 0, pipe_cnt = 0; i < dc->res_pool->pipe_count; i++) {
 
 		if (!res_ctx->pipe_ctx[i].stream)
@@ -1832,6 +1870,18 @@ int dcn32_populate_dml_pipes_from_context(
 		pipes[pipe_cnt].pipe.dest.vfront_porch = timing->v_front_porch;
 		if (dc->config.enable_windowed_mpo_odm &&
 				dc->debug.enable_single_display_2to1_odm_policy) {
+			/* For single display subvp, if pipe is phantom pipe,
+			 *  then copy odm policy from subvp main pipe
+			 */
+			mall_type = dc_state_get_pipe_subvp_type(context, pipe);
+			if (single_display_subvp && (mall_type == SUBVP_PHANTOM)) {
+				if (subvp_main_pipe_index < 0) {
+					ASSERT(0);
+				} else {
+					pipes[pipe_cnt].pipe.dest.odm_combine_policy =
+						pipes[subvp_main_pipe_index].pipe.dest.odm_combine_policy;
+				}
+			} else {
 				switch (resource_get_odm_slice_count(pipe)) {
 				case 2:
 					pipes[pipe_cnt].pipe.dest.odm_combine_policy = dm_odm_combine_policy_2to1;
@@ -1842,9 +1892,11 @@ int dcn32_populate_dml_pipes_from_context(
 				default:
 					pipes[pipe_cnt].pipe.dest.odm_combine_policy = dm_odm_combine_policy_dal;
 				}
+			}
 		} else {
 			pipes[pipe_cnt].pipe.dest.odm_combine_policy = dm_odm_combine_policy_dal;
 		}
+
 		pipes[pipe_cnt].pipe.src.gpuvm_min_page_size_kbytes = 256; // according to spreadsheet
 		pipes[pipe_cnt].pipe.src.unbounded_req_mode = false;
 		pipes[pipe_cnt].pipe.scale_ratio_depth.lb_depth = dm_lb_19;