Nouveau - Sep 2019 - [PATCH AUTOSEL 4.14 21/28] drm/nouveau/volt: Fix for some cards having 0 maximum voltage

From: Mark Menzynski <mmenzyns at redhat.com>

[ Upstream commit a1af2afbd244089560794c260b2d4326a86e39b6 ]

Some, mostly Fermi, vbioses appear to have zero max voltage. That causes Nouveau
to not parse voltage entries, thus users not being able to set higher clocks.

When changing this value Nvidia driver still appeared to ignore it, and I
wasn't able to find out why, thus the code is ignoring the value if it is
zero.

CC: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Signed-off-by: Mark Menzynski <mmenzyns at redhat.com>
Reviewed-by: Karol Herbst <kherbst at redhat.com>
Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c
b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c
index 7143ea4611aa3..33a9fb5ac5585 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/volt.c
@@ -96,6 +96,8 @@ nvbios_volt_parse(struct nvkm_bios *bios, u8 *ver, u8 *hdr, u8
*cnt, u8 *len,
 		info->min     = min(info->base,
 				    info->base + info->step * info->vidmask);
 		info->max     = nvbios_rd32(bios, volt + 0x0e);
+		if (!info->max)
+			info->max = max(info->base, info->base + info->step *
info->vidmask);
 		break;
 	case 0x50:
 		info->min     = nvbios_rd32(bios, volt + 0x0a);
-- 
2.20.1