drm/nouveau/therm: let the vbios decide on the automatic fan management mode

This should fix automatic fan management on fermi cards who do not have
0x46 entries in the thermal table.

On my nve6, the blob sets the default linear range from 40°C to 100°C
but my nvcf's default values are 40°C to 85°C. Let's keep 85 as a default
for everyone.
Signed-off-by: Martin Peres <martin.peres@labri.fr>
Tested-by: Timothée Ravier <tim@siosm.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/include/subdev/bios/therm.h

@@ -31,6 +31,12 @@ struct nouveau_therm_trip_point {
 	int hysteresis;
 };
 
+enum nvbios_therm_fan_mode {
+	NVBIOS_THERM_FAN_TRIP = 0,
+	NVBIOS_THERM_FAN_LINEAR = 1,
+	NVBIOS_THERM_FAN_OTHER = 2,
+};
+
 struct nvbios_therm_fan {
 	u16 pwm_freq;
 
@@ -40,6 +46,7 @@ struct nvbios_therm_fan {
 	u16 bump_period;
 	u16 slow_down_period;
 
+	enum nvbios_therm_fan_mode fan_mode;
 	struct nouveau_therm_trip_point trip[NOUVEAU_TEMP_FAN_TRIP_MAX];
 	u8 nr_fan_trip;
 	u8 linear_min_temp;

drivers/gpu/drm/nouveau/core/subdev/bios/therm.c

@@ -164,6 +164,7 @@ nvbios_therm_fan_parse(struct nouveau_bios *bios,
 
 	i = 0;
 	fan->nr_fan_trip = 0;
+	fan->fan_mode = NVBIOS_THERM_FAN_OTHER;
 	while ((entry = nvbios_therm_entry(bios, i++, &ver, &len))) {
 		s16 value = nv_ro16(bios, entry + 1);
 
@@ -174,6 +175,8 @@ nvbios_therm_fan_parse(struct nouveau_bios *bios,
 			break;
 		case 0x24:
 			fan->nr_fan_trip++;
+			if (fan->fan_mode > NVBIOS_THERM_FAN_TRIP)
+				fan->fan_mode = NVBIOS_THERM_FAN_TRIP;
 			cur_trip = &fan->trip[fan->nr_fan_trip - 1];
 			cur_trip->hysteresis = value & 0xf;
 			cur_trip->temp = (value & 0xff0) >> 4;
@@ -194,11 +197,19 @@ nvbios_therm_fan_parse(struct nouveau_bios *bios,
 			fan->slow_down_period = value;
 			break;
 		case 0x46:
+			if (fan->fan_mode > NVBIOS_THERM_FAN_LINEAR)
+				fan->fan_mode = NVBIOS_THERM_FAN_LINEAR;
 			fan->linear_min_temp = nv_ro08(bios, entry + 1);
 			fan->linear_max_temp = nv_ro08(bios, entry + 2);
 			break;
 		}
 	}
 
+	/* starting from fermi, fan management is always linear */
+	if (nv_device(bios)->card_type >= NV_C0 &&
+		fan->fan_mode == NVBIOS_THERM_FAN_OTHER) {
+		fan->fan_mode = NVBIOS_THERM_FAN_LINEAR;
+	}
+
 	return 0;
 }

drivers/gpu/drm/nouveau/core/subdev/therm/base.c

@@ -110,16 +110,18 @@ nouveau_therm_update(struct nouveau_therm *therm, int mode)
 		poll = false;
 		break;
 	case NOUVEAU_THERM_CTRL_AUTO:
-		if (priv->fan->bios.nr_fan_trip) {
+		switch(priv->fan->bios.fan_mode) {
+		case NVBIOS_THERM_FAN_TRIP:
 			duty = nouveau_therm_update_trip(therm);
-		} else
-		if (priv->fan->bios.linear_min_temp ||
-		    priv->fan->bios.linear_max_temp) {
+			break;
+		case NVBIOS_THERM_FAN_LINEAR:
 			duty = nouveau_therm_update_linear(therm);
-		} else {
+			break;
+		case NVBIOS_THERM_FAN_OTHER:
 			if (priv->cstate)
 				duty = priv->cstate;
 			poll = false;
+			break;
 		}
 		immd = false;
 		break;

drivers/gpu/drm/nouveau/core/subdev/therm/fan.c

@@ -192,11 +192,8 @@ nouveau_therm_fan_set_defaults(struct nouveau_therm *therm)
 	priv->fan->bios.max_duty = 100;
 	priv->fan->bios.bump_period = 500;
 	priv->fan->bios.slow_down_period = 2000;
-/*XXX: talk to mupuf */
-#if 0
 	priv->fan->bios.linear_min_temp = 40;
 	priv->fan->bios.linear_max_temp = 85;
-#endif
 }
 
 static void