drm/amd/pm: fix null ptr access

check null ptr first before access its element

v2: check adev->pm.dpm_enabled early in amdgpu_debugfs_pm_init()
Signed-off-by: Flora Cui <flora.cui@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/amdgpu_dpm.c

@@ -463,7 +463,7 @@ int amdgpu_pm_load_smu_firmware(struct amdgpu_device *adev, uint32_t *smu_versio
 	const struct amd_pm_funcs *pp_funcs = adev->powerplay.pp_funcs;
 	int r = 0;
 
-	if (!pp_funcs->load_firmware)
+	if (!pp_funcs || !pp_funcs->load_firmware)
 		return 0;
 
 	mutex_lock(&adev->pm.mutex);

drivers/gpu/drm/amd/pm/amdgpu_pm.c

@@ -3583,6 +3583,9 @@ void amdgpu_debugfs_pm_init(struct amdgpu_device *adev)
 	struct drm_minor *minor = adev_to_drm(adev)->primary;
 	struct dentry *root = minor->debugfs_root;
 
+	if (!adev->pm.dpm_enabled)
+		return;
+
 	debugfs_create_file("amdgpu_pm_info", 0444, root, adev,
 			    &amdgpu_debugfs_pm_info_fops);