drm/amd/display: do not force UCLK DPM to stay at highest state during display off in DCN2

[Why]
Add optimization to allow pstate change support when all displays
are off in DCN2.

[How]
Add clk_mgr_helper_get_active_plane_cnt() to sum plane_count for all
valid stream_status[].  If plane_count is 0, then there are no active
or virtual streams present. Use plane_count == 0 as extra condition to
enable p_state_change_support in dcn2_update_clocks().
Signed-off-by: Samson Tam <Samson.Tam@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@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/clk_mgr/clk_mgr.c

@@ -63,6 +63,25 @@ int clk_mgr_helper_get_active_display_cnt(
 	return display_count;
 }
 
+int clk_mgr_helper_get_active_plane_cnt(
+		struct dc *dc,
+		struct dc_state *context)
+{
+	int i, total_plane_count;
+
+	total_plane_count = 0;
+	for (i = 0; i < context->stream_count; i++) {
+		const struct dc_stream_status stream_status = context->stream_status[i];
+
+		/*
+		 * Sum up plane_count for all streams ( active and virtual ).
+		 */
+		total_plane_count += stream_status.plane_count;
+	}
+
+	return total_plane_count;
+}
+
 void clk_mgr_exit_optimized_pwr_state(const struct dc *dc, struct clk_mgr *clk_mgr)
 {
 	struct dc_link *edp_link = get_edp_link(dc);

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn20/dcn20_clk_mgr.c

@@ -158,6 +158,8 @@ void dcn2_update_clocks(struct clk_mgr *clk_mgr_base,
 	bool dpp_clock_lowered = false;
 	struct dmcu *dmcu = clk_mgr_base->ctx->dc->res_pool->dmcu;
 	bool force_reset = false;
+	bool p_state_change_support;
+	int total_plane_count;
 
 	if (dc->work_arounds.skip_clock_update)
 		return;
@@ -213,9 +215,11 @@ void dcn2_update_clocks(struct clk_mgr *clk_mgr_base,
 			pp_smu->set_hard_min_socclk_by_freq(&pp_smu->pp_smu, clk_mgr_base->clks.socclk_khz / 1000);
 	}
 
-	if (should_update_pstate_support(safe_to_lower, new_clocks->p_state_change_support, clk_mgr_base->clks.p_state_change_support)) {
+	total_plane_count = clk_mgr_helper_get_active_plane_cnt(dc, context);
+	p_state_change_support = new_clocks->p_state_change_support || (total_plane_count == 0);
+	if (should_update_pstate_support(safe_to_lower, p_state_change_support, clk_mgr_base->clks.p_state_change_support)) {
 		clk_mgr_base->clks.prev_p_state_change_support = clk_mgr_base->clks.p_state_change_support;
-		clk_mgr_base->clks.p_state_change_support = new_clocks->p_state_change_support;
+		clk_mgr_base->clks.p_state_change_support = p_state_change_support;
 		if (pp_smu && pp_smu->set_pstate_handshake_support)
 			pp_smu->set_pstate_handshake_support(&pp_smu->pp_smu, clk_mgr_base->clks.p_state_change_support);
 	}

drivers/gpu/drm/amd/display/dc/inc/hw/clk_mgr_internal.h

@@ -296,6 +296,10 @@ int clk_mgr_helper_get_active_display_cnt(
 		struct dc *dc,
 		struct dc_state *context);
 
+int clk_mgr_helper_get_active_plane_cnt(
+		struct dc *dc,
+		struct dc_state *context);
+
 
 
 #endif //__DAL_CLK_MGR_INTERNAL_H__