[PATCH] drm/amdgpu: Check if smu.ppt_funcs is initialized before accessing

[sunpeng.li at amd.com]

From: Leo Li <sunpeng.li at amd.com>

smu.ppt_funcs is only initialized for specific SMU versions.

On a Hawaii ASIC, attempting to access the udev attribute
ATTRS{power_dpm_state} will cause a null pointer deref in
amdgpu_get_dpm_state() because of this.

Fix by checking that ppt_funcs is initialized first.

CC: Chengming Gui <Jack.Gui at amd.com>
Signed-off-by: Leo Li <sunpeng.li at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index 4b7a076..7993623 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -144,7 +144,7 @@ static ssize_t amdgpu_get_dpm_state(struct device *dev,
 	struct amdgpu_device *adev = ddev->dev_private;
 	enum amd_pm_state_type pm;
 
-	if (adev->smu.ppt_funcs->get_current_power_state)
+	if (adev->smu.ppt_funcs && adev->smu.ppt_funcs->get_current_power_state)
 		pm = amdgpu_smu_get_current_power_state(adev);
 	else if (adev->powerplay.pp_funcs->get_current_power_state)
 		pm = amdgpu_dpm_get_current_power_state(adev);
-- 
2.7.4