drm/nouveau/volt: Properly detect entry based voltage tables

There is a field in the voltage table which tells us if the VIDs are taken
from the entries or calculated through the header.

v2: Don't break older versions.
v5: Reverse flag name.
Signed-off-by: Karol Herbst <karolherbst@gmail.com>
Reviewed-by: Martin Peres <martin.peres@free.fr>
Tested-by: Pierre Moreau <pierre.morrow@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/subdev/bios/volt.h

@@ -13,8 +13,9 @@ struct nvbios_volt {
 	u32 base;
 
 	/* GPIO mode */
-	u8  vidmask;
-	s16 step;
+	bool ranged;
+	u8   vidmask;
+	s16  step;
 
 	/* PWM mode */
 	u32 pwm_freq;

drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c

@@ -75,20 +75,24 @@ nvbios_volt_parse(struct nvkm_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len,
 	case 0x12:
 		info->type    = NVBIOS_VOLT_GPIO;
 		info->vidmask = nvbios_rd08(bios, volt + 0x04);
+		info->ranged  = false;
 		break;
 	case 0x20:
 		info->type    = NVBIOS_VOLT_GPIO;
 		info->vidmask = nvbios_rd08(bios, volt + 0x05);
+		info->ranged  = false;
 		break;
 	case 0x30:
 		info->type    = NVBIOS_VOLT_GPIO;
 		info->vidmask = nvbios_rd08(bios, volt + 0x04);
+		info->ranged  = false;
 		break;
 	case 0x40:
 		info->type    = NVBIOS_VOLT_GPIO;
 		info->base    = nvbios_rd32(bios, volt + 0x04);
 		info->step    = nvbios_rd16(bios, volt + 0x08);
 		info->vidmask = nvbios_rd08(bios, volt + 0x0b);
+		info->ranged  = true; /* XXX: find the flag byte */
 		/*XXX*/
 		info->min     = 0;
 		info->max     = info->base;
@@ -104,9 +108,11 @@ nvbios_volt_parse(struct nvkm_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len,
 			info->pwm_freq  = nvbios_rd32(bios, volt + 0x5) / 1000;
 			info->pwm_range = nvbios_rd32(bios, volt + 0x16);
 		} else {
-			info->type      = NVBIOS_VOLT_GPIO;
-			info->vidmask   = nvbios_rd08(bios, volt + 0x06);
-			info->step      = nvbios_rd16(bios, volt + 0x16);
+			info->type    = NVBIOS_VOLT_GPIO;
+			info->vidmask = nvbios_rd08(bios, volt + 0x06);
+			info->step    = nvbios_rd16(bios, volt + 0x16);
+			info->ranged  =
+				!!(nvbios_rd08(bios, volt + 0x4) & 0x2);
 		}
 		break;
 	}

drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c

@@ -112,6 +112,7 @@ nvkm_volt_set_id(struct nvkm_volt *volt, u8 id, int condition)
 static void
 nvkm_volt_parse_bios(struct nvkm_bios *bios, struct nvkm_volt *volt)
 {
+	struct nvkm_subdev *subdev = &bios->subdev;
 	struct nvbios_volt_entry ivid;
 	struct nvbios_volt info;
 	u8  ver, hdr, cnt, len;
@@ -119,7 +120,8 @@ nvkm_volt_parse_bios(struct nvkm_bios *bios, struct nvkm_volt *volt)
 	int i;
 
 	data = nvbios_volt_parse(bios, &ver, &hdr, &cnt, &len, &info);
-	if (data && info.vidmask && info.base && info.step) {
+	if (data && info.vidmask && info.base && info.step && info.ranged) {
+		nvkm_debug(subdev, "found ranged based VIDs\n");
 		volt->min_uv = info.min;
 		volt->max_uv = info.max;
 		for (i = 0; i < info.vidmask + 1; i++) {
@@ -132,7 +134,8 @@ nvkm_volt_parse_bios(struct nvkm_bios *bios, struct nvkm_volt *volt)
 			info.base += info.step;
 		}
 		volt->vid_mask = info.vidmask;
-	} else if (data && info.vidmask) {
+	} else if (data && info.vidmask && !info.ranged) {
+		nvkm_debug(subdev, "found entry based VIDs\n");
 		volt->min_uv = 0xffffffff;
 		volt->max_uv = 0;
 		for (i = 0; i < cnt; i++) {