drm/nouveau/pm: allow voltage-only perflvl set, enable nvc0

Okay, my card didn't blow up.  Lets turn it on!
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_pm.c

@@ -72,10 +72,12 @@ nouveau_pm_perflvl_set(struct drm_device *dev, struct nouveau_pm_level *perflvl)
 		}
 	}
 
-	nouveau_pm_clock_set(dev, perflvl, PLL_CORE, perflvl->core);
-	nouveau_pm_clock_set(dev, perflvl, PLL_SHADER, perflvl->shader);
-	nouveau_pm_clock_set(dev, perflvl, PLL_MEMORY, perflvl->memory);
-	nouveau_pm_clock_set(dev, perflvl, PLL_UNK05, perflvl->unk05);
+	if (pm->clock_set) {
+		nouveau_pm_clock_set(dev, perflvl, PLL_CORE, perflvl->core);
+		nouveau_pm_clock_set(dev, perflvl, PLL_SHADER, perflvl->shader);
+		nouveau_pm_clock_set(dev, perflvl, PLL_MEMORY, perflvl->memory);
+		nouveau_pm_clock_set(dev, perflvl, PLL_UNK05, perflvl->unk05);
+	}
 
 	pm->cur = perflvl;
 	return 0;
@@ -92,9 +94,6 @@ nouveau_pm_profile_set(struct drm_device *dev, const char *profile)
 	if (nouveau_perflvl_wr != 7777)
 		return -EPERM;
 
-	if (!pm->clock_set)
-		return -EINVAL;
-
 	if (!strncmp(profile, "boot", 4))
 		perflvl = &pm->boot;
 	else {

drivers/gpu/drm/nouveau/nouveau_state.c

@@ -423,6 +423,7 @@ static int nouveau_init_engine_ptrs(struct drm_device *dev)
 		engine->vram.flags_valid	= nvc0_vram_flags_valid;
 		engine->pm.temp_get		= nv84_temp_get;
 		engine->pm.voltage_get		= nouveau_voltage_gpio_get;
+		engine->pm.voltage_set		= nouveau_voltage_gpio_set;
 		break;
 	default:
 		NV_ERROR(dev, "NV%02x unsupported\n", dev_priv->chipset);