drm/amd/pm: Fix negative array index read

Avoid using the negative values
for clk_idex as an index into an array pptable->DpmDescriptor.

V2: fix clk_index return check (Tim Huang)
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Tim Huang <Tim.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c

@@ -1219,19 +1219,22 @@ static int navi10_get_current_clk_freq_by_table(struct smu_context *smu,
 					   value);
 }
 
-static bool navi10_is_support_fine_grained_dpm(struct smu_context *smu, enum smu_clk_type clk_type)
+static int navi10_is_support_fine_grained_dpm(struct smu_context *smu, enum smu_clk_type clk_type)
 {
 	PPTable_t *pptable = smu->smu_table.driver_pptable;
 	DpmDescriptor_t *dpm_desc = NULL;
-	uint32_t clk_index = 0;
+	int clk_index = 0;
 
 	clk_index = smu_cmn_to_asic_specific_index(smu,
 						   CMN2ASIC_MAPPING_CLK,
 						   clk_type);
+	if (clk_index < 0)
+		return clk_index;
+
 	dpm_desc = &pptable->DpmDescriptor[clk_index];
 
 	/* 0 - Fine grained DPM, 1 - Discrete DPM */
-	return dpm_desc->SnapToDiscrete == 0;
+	return dpm_desc->SnapToDiscrete == 0 ? 1 : 0;
 }
 
 static inline bool navi10_od_feature_is_supported(struct smu_11_0_overdrive_table *od_table, enum SMU_11_0_ODFEATURE_CAP cap)
@@ -1287,7 +1290,11 @@ static int navi10_emit_clk_levels(struct smu_context *smu,
 		if (ret)
 			return ret;
 
-		if (!navi10_is_support_fine_grained_dpm(smu, clk_type)) {
+		ret = navi10_is_support_fine_grained_dpm(smu, clk_type);
+		if (ret < 0)
+			return ret;
+
+		if (!ret) {
 			for (i = 0; i < count; i++) {
 				ret = smu_v11_0_get_dpm_freq_by_index(smu,
 								      clk_type, i, &value);
@@ -1496,7 +1503,11 @@ static int navi10_print_clk_levels(struct smu_context *smu,
 		if (ret)
 			return size;
 
-		if (!navi10_is_support_fine_grained_dpm(smu, clk_type)) {
+		ret = navi10_is_support_fine_grained_dpm(smu, clk_type);
+		if (ret < 0)
+			return ret;
+
+		if (!ret) {
 			for (i = 0; i < count; i++) {
 				ret = smu_v11_0_get_dpm_freq_by_index(smu, clk_type, i, &value);
 				if (ret)
@@ -1665,7 +1676,11 @@ static int navi10_force_clk_levels(struct smu_context *smu,
 	case SMU_UCLK:
 	case SMU_FCLK:
 		/* There is only 2 levels for fine grained DPM */
-		if (navi10_is_support_fine_grained_dpm(smu, clk_type)) {
+		ret = navi10_is_support_fine_grained_dpm(smu, clk_type);
+		if (ret < 0)
+			return ret;
+
+		if (ret) {
 			soft_max_level = (soft_max_level >= 1 ? 1 : 0);
 			soft_min_level = (soft_min_level >= 1 ? 1 : 0);
 		}