diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/iccsense.c b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/iccsense.c
index 3953d11844ea008ee4137e6e2441c7f12b808e91..23caef8df17fbd13638a7f778bd8ffeca41321d2 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/iccsense.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/iccsense.c
@@ -87,7 +87,10 @@ nvbios_iccsense_parse(struct nvkm_bios *bios, struct nvbios_iccsense *iccsense)
 
 		switch(ver) {
 		case 0x10:
-			rail->mode = nvbios_rd08(bios, entry + 0x1);
+			if ((nvbios_rd08(bios, entry + 0x1) & 0xf8) == 0xf8)
+				rail->mode = 1;
+			else
+				rail->mode = 0;
 			rail->extdev_id = nvbios_rd08(bios, entry + 0x2);
 			res_start = 0x3;
 			break;