drm/amd/powerplay: use hardware fan control if no powerplay fan table

Otherwise, you may get divided-by-zero error or corrput the SMU fan
control feature.
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Tested-by: Slava Abramov <slava.abramov@amd.com>
Acked-by: Slava Abramov <slava.abramov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/powerplay/hwmgr/process_pptables_v1_0.c

@@ -916,8 +916,10 @@ static int init_thermal_controller(
 			PHM_PlatformCaps_ThermalController
 		  );
 
-	if (0 == powerplay_table->usFanTableOffset)
+	if (0 == powerplay_table->usFanTableOffset) {
+		hwmgr->thermal_controller.use_hw_fan_control = 1;
 		return 0;
+	}
 
 	fan_table = (const PPTable_Generic_SubTable_Header *)
 		(((unsigned long)powerplay_table) +

drivers/gpu/drm/amd/powerplay/inc/hwmgr.h

@@ -694,6 +694,7 @@ struct pp_thermal_controller_info {
 	uint8_t ucType;
 	uint8_t ucI2cLine;
 	uint8_t ucI2cAddress;
+	uint8_t use_hw_fan_control;
 	struct pp_fan_info fanInfo;
 	struct pp_advance_fan_control_parameters advanceFanControlParameters;
 };

drivers/gpu/drm/amd/powerplay/smumgr/polaris10_smumgr.c

@@ -2092,6 +2092,10 @@ static int polaris10_thermal_setup_fan_table(struct pp_hwmgr *hwmgr)
 		return 0;
 	}
 
+	/* use hardware fan control */
+	if (hwmgr->thermal_controller.use_hw_fan_control)
+		return 0;
+
 	tmp64 = hwmgr->thermal_controller.advanceFanControlParameters.
 			usPWMMin * duty100;
 	do_div(tmp64, 10000);