drm/radeon/kms/r6xx+: voltage fixes

0xff01 is not an actual voltage value, but a flag
for the driver.  If the power state as that value,
skip setting the voltage.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index dc9fde3..f79d2cc 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -590,6 +590,9 @@
 	struct radeon_voltage *voltage = &ps->clock_info[req_cm_idx].voltage;
 
 	if ((voltage->type == VOLTAGE_SW) && voltage->voltage) {
+		/* 0xff01 is a flag rather then an actual voltage */
+		if (voltage->voltage == 0xff01)
+			return;
 		if (voltage->voltage != rdev->pm.current_vddc) {
 			radeon_atom_set_voltage(rdev, voltage->voltage, SET_VOLTAGE_TYPE_ASIC_VDDC);
 			rdev->pm.current_vddc = voltage->voltage;