drm/amd/display: enable optional pipe split for single display

also refactor debug option.  now pipe_split_policy are
dynamic = no hack around dcn_calcs.  will split based on HW recommendation
avoid = avoid split if we can support the config with higher voltage
avoid_multi_display = allow split with single display output.

force_single_disp_pipe_split
force single display to pipe split to improve stutter efficiency
by using DET buffers using 2 HUBP.
Signed-off-by: Tony Cheng <tony.cheng@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/calcs/dcn_calcs.c

@@ -720,6 +720,46 @@ static bool dcn_bw_apply_registry_override(struct dc *dc)
 	return updated;
 }
 
+void hack_disable_optional_pipe_split(struct dcn_bw_internal_vars *v)
+{
+	/*
+	 * disable optional pipe split by lower dispclk bounding box
+	 * at DPM0
+	 */
+	v->max_dispclk[0] = v->max_dppclk_vmin0p65;
+}
+
+void hack_force_pipe_split(struct dcn_bw_internal_vars *v,
+		unsigned int pixel_rate_khz)
+{
+	/*
+	 * force enabling pipe split by lower dpp clock for DPM0 to just
+	 * below the specify pixel_rate, so bw calc would split pipe.
+	 */
+	v->max_dppclk[0] = pixel_rate_khz / 1000;
+}
+
+void hack_bounding_box(struct dcn_bw_internal_vars *v,
+		struct dc_debug *dbg,
+		struct dc_state *context)
+{
+	if (dbg->pipe_split_policy == MPC_SPLIT_AVOID) {
+		hack_disable_optional_pipe_split(v);
+	}
+
+	if (dbg->pipe_split_policy == MPC_SPLIT_AVOID_MULT_DISP &&
+		context->stream_count >= 2) {
+		hack_disable_optional_pipe_split(v);
+	}
+
+	if (context->stream_count == 1 &&
+			dbg->force_single_disp_pipe_split) {
+		struct dc_stream_state *stream0 = context->streams[0];
+
+		hack_force_pipe_split(v, stream0->timing.pix_clk_khz);
+	}
+}
+
 bool dcn_validate_bandwidth(
 		struct dc *dc,
 		struct dc_state *context)
@@ -851,9 +891,7 @@ bool dcn_validate_bandwidth(
 	v->phyclk_per_state[1] = v->phyclkv_mid0p72;
 	v->phyclk_per_state[0] = v->phyclkv_min0p65;
 
-	if (dc->debug.disable_pipe_split) {
-		v->max_dispclk[0] = v->max_dppclk_vmin0p65;
-	}
+	hack_bounding_box(v, &dc->debug, context);
 
 	if (v->voltage_override == dcn_bw_v_max0p9) {
 		v->voltage_override_level = number_of_states - 1;

drivers/gpu/drm/amd/display/dc/dc.h

@@ -162,6 +162,12 @@ struct dc_config {
 	bool disable_disp_pll_sharing;
 };
 
+enum pipe_split_policy {
+	MPC_SPLIT_DYNAMIC = 0,
+	MPC_SPLIT_AVOID = 1,
+	MPC_SPLIT_AVOID_MULT_DISP = 2,
+};
+
 struct dc_debug {
 	bool surface_visual_confirm;
 	bool sanity_checks;
@@ -177,7 +183,8 @@ struct dc_debug {
 	bool disable_hubp_power_gate;
 	bool disable_pplib_wm_range;
 	bool use_dml_wm;
-	bool disable_pipe_split;
+	enum pipe_split_policy pipe_split_policy;
+	bool force_single_disp_pipe_split;
 	unsigned int min_disp_clk_khz;
 	int sr_exit_time_dpm0_ns;
 	int sr_enter_plus_exit_time_dpm0_ns;

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_resource.c

@@ -425,10 +425,9 @@ static const struct dc_debug debug_defaults_drv = {
 
 		.disable_pplib_clock_request = true,
 		.disable_pplib_wm_range = false,
-#if defined(CONFIG_DRM_AMD_DC_DCN1_0)
 		.use_dml_wm = false,
-		.disable_pipe_split = true
-#endif
+
+		.pipe_split_policy = MPC_SPLIT_AVOID_MULT_DISP,
 };
 
 static const struct dc_debug debug_defaults_diags = {
@@ -437,12 +436,9 @@ static const struct dc_debug debug_defaults_diags = {
 		.timing_trace = true,
 		.clock_trace = true,
 		.disable_stutter = true,
-#if defined(CONFIG_DRM_AMD_DC_DCN1_0)
 		.disable_pplib_clock_request = true,
 		.disable_pplib_wm_range = true,
 		.use_dml_wm = false,
-		.disable_pipe_split = false
-#endif
 };
 
 static void dcn10_dpp_destroy(struct transform **xfm)