drm/amd/display: Correct bw_params population

[Why]
Underflow observed during P010 video playback on
dcn314 due to incorrectly populated bw_params

[How]
Populate fclk, memclk and voltage in bw_params with
values from max pstate rather than min pstate
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Daniel Miess <Daniel.Miess@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/clk_mgr/dcn314/dcn314_clk_mgr.c

@@ -572,10 +572,11 @@ static void dcn314_clk_mgr_helper_populate_bw_params(struct clk_mgr_internal *cl
 {
 	struct clk_bw_params *bw_params = clk_mgr->base.bw_params;
 	struct clk_limit_table_entry def_max = bw_params->clk_table.entries[bw_params->clk_table.num_entries - 1];
-	uint32_t max_pstate = 0,  max_fclk = 0,  min_pstate = 0, max_dispclk = 0, max_dppclk = 0;
+	uint32_t max_pstate = 0, max_fclk = 0, max_dispclk = 0, max_dppclk = 0;
+	uint32_t min_pstate = 0, min_fclk = clock_table->DfPstateTable[0].FClk;
 	int i;
 
-	/* Find highest valid fclk pstate */
+	/* Find highest and lowest valid fclk pstate */
 	for (i = 0; i < clock_table->NumDfPstatesEnabled; i++) {
 		if (is_valid_clock_value(clock_table->DfPstateTable[i].FClk) &&
 		    clock_table->DfPstateTable[i].FClk > max_fclk) {
@@ -584,6 +585,14 @@ static void dcn314_clk_mgr_helper_populate_bw_params(struct clk_mgr_internal *cl
 		}
 	}
 
+	for (i = 0; i < clock_table->NumDfPstatesEnabled; i++) {
+		if (is_valid_clock_value(clock_table->DfPstateTable[i].FClk) &&
+		    clock_table->DfPstateTable[i].FClk < min_fclk) {
+			min_fclk = clock_table->DfPstateTable[i].FClk;
+			min_pstate = i;
+		}
+	}
+
 	/* We expect the table to contain at least one valid fclk entry. */
 	ASSERT(is_valid_clock_value(max_fclk));
 
@@ -599,15 +608,17 @@ static void dcn314_clk_mgr_helper_populate_bw_params(struct clk_mgr_internal *cl
 
 	/* Base the clock table on dcfclk, need at least one entry regardless of pmfw table */
 	for (i = 0; i < clock_table->NumDcfClkLevelsEnabled; i++) {
-		uint32_t min_fclk = clock_table->DfPstateTable[0].FClk;
+		uint32_t max_level_fclk = clock_table->DfPstateTable[0].FClk;
+		uint32_t max_level_pstate = 0;
 		int j;
 
+		/* Look for the maximum supported FCLK for the current voltage. */
 		for (j = 1; j < clock_table->NumDfPstatesEnabled; j++) {
 			if (is_valid_clock_value(clock_table->DfPstateTable[j].FClk) &&
-			    clock_table->DfPstateTable[j].FClk < min_fclk &&
+			    clock_table->DfPstateTable[j].FClk > max_level_fclk &&
 			    clock_table->DfPstateTable[j].Voltage <= clock_table->SocVoltage[i]) {
-				min_fclk = clock_table->DfPstateTable[j].FClk;
-				min_pstate = j;
+				max_level_fclk = clock_table->DfPstateTable[j].FClk;
+				max_level_pstate = j;
 			}
 		}
 
@@ -621,15 +632,15 @@ static void dcn314_clk_mgr_helper_populate_bw_params(struct clk_mgr_internal *cl
 		bw_params->clk_table.entries[i].dtbclk_mhz = bw_params->clk_table.entries[j].dtbclk_mhz;
 
 		/* Now update clocks we do read */
-		bw_params->clk_table.entries[i].fclk_mhz = min_fclk;
-		bw_params->clk_table.entries[i].memclk_mhz = clock_table->DfPstateTable[min_pstate].MemClk;
-		bw_params->clk_table.entries[i].voltage = clock_table->DfPstateTable[min_pstate].Voltage;
+		bw_params->clk_table.entries[i].fclk_mhz = max_level_fclk;
+		bw_params->clk_table.entries[i].memclk_mhz = clock_table->DfPstateTable[max_level_pstate].MemClk;
+		bw_params->clk_table.entries[i].voltage = clock_table->DfPstateTable[max_level_pstate].Voltage;
 		bw_params->clk_table.entries[i].dcfclk_mhz = clock_table->DcfClocks[i];
 		bw_params->clk_table.entries[i].socclk_mhz = clock_table->SocClocks[i];
 		bw_params->clk_table.entries[i].dispclk_mhz = max_dispclk;
 		bw_params->clk_table.entries[i].dppclk_mhz = max_dppclk;
 		bw_params->clk_table.entries[i].wck_ratio = convert_wck_ratio(
-			clock_table->DfPstateTable[min_pstate].WckRatio);
+			clock_table->DfPstateTable[max_level_pstate].WckRatio);
 	}
 
 	/* Make sure to include at least one entry at highest pstate */