[PATCH] drm/radeon/kms/atom: fix possible segfault in pm setup

[alexdeucher at gmail.com]

From: Alexander Müller <serveralex at gmail.com>

If we end up with no power states, don't look up
current vddc.

fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=44130

agd5f: fix patch formatting

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/radeon/radeon_atombios.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index dc7c751..a9ce094 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -2595,7 +2595,11 @@ void radeon_atombios_get_power_modes(struct radeon_device *rdev)
 
 	rdev->pm.current_power_state_index = rdev->pm.default_power_state_index;
 	rdev->pm.current_clock_mode_index = 0;
-	rdev->pm.current_vddc = rdev->pm.power_state[rdev->pm.default_power_state_index].clock_info[0].voltage.voltage;
+	if (rdev->pm.default_power_state_index >= 0)
+		rdev->pm.current_vddc =
+			rdev->pm.power_state[rdev->pm.default_power_state_index].clock_info[0].voltage.voltage;
+	else
+		rdev->pm.current_vddc = 0;
 }
 
 void radeon_atom_set_clock_gating(struct radeon_device *rdev, int enable)
-- 
1.7.3.4