drm/amd/powerplay: fix a crash when overclocking Vega M

Avoid kernel crash when vddci_control is SMU7_VOLTAGE_CONTROL_NONE and
vddci_voltage_table is empty. It has been tested on Intel Hades Canyon
(i7-8809G).

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=208489
Fixes: ac7822b ("drm/amd/powerplay: add smumgr support for VEGAM (v2)")
Reviewed-by: Evan Quan <[email protected]>
Signed-off-by: Qiu Wenbo <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: crab2313

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

@@ -644,18 +644,20 @@ static int vegam_get_dependency_volt_by_clk(struct pp_hwmgr *hwmgr,
 
 	/* sclk is bigger than max sclk in the dependence table */
 	*voltage |= (dep_table->entries[i - 1].vddc * VOLTAGE_SCALE) << VDDC_SHIFT;
-	vddci = phm_find_closest_vddci(&(data->vddci_voltage_table),
-			(dep_table->entries[i - 1].vddc -
-					(uint16_t)VDDC_VDDCI_DELTA));
 
 	if (SMU7_VOLTAGE_CONTROL_NONE == data->vddci_control)
 		*voltage |= (data->vbios_boot_state.vddci_bootup_value *
 				VOLTAGE_SCALE) << VDDCI_SHIFT;
 	else if (dep_table->entries[i - 1].vddci)
 		*voltage |= (dep_table->entries[i - 1].vddci *
 				VOLTAGE_SCALE) << VDDC_SHIFT;
-	else
+	else {
+		vddci = phm_find_closest_vddci(&(data->vddci_voltage_table),
+				(dep_table->entries[i - 1].vddc -
+						(uint16_t)VDDC_VDDCI_DELTA));
+
 		*voltage |= (vddci * VOLTAGE_SCALE) << VDDCI_SHIFT;
+	}
 
 	if (SMU7_VOLTAGE_CONTROL_NONE == data->mvdd_control)
 		*mvdd = data->vbios_boot_state.mvdd_bootup_value * VOLTAGE_SCALE;