drm/amdgpu: check function points valid before use. (v3)

v2: agd: integrate Christian's comments.
v3: print error message if call fails

Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Rex Zhu <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

···
 	for (i = 0; i < adev->num_ip_blocks; i++) {
 		if (!adev->ip_blocks[i].status.valid)
 			continue;
-		if (adev->ip_blocks[i].version->type == block_type) {
-			r = adev->ip_blocks[i].version->funcs->set_clockgating_state((void *)adev,
-										     state);
-			if (r)
-				return r;
-			break;
-		}
+		if (adev->ip_blocks[i].version->type != block_type)
+			continue;
+		if (!adev->ip_blocks[i].version->funcs->set_clockgating_state)
+			continue;
+		r = adev->ip_blocks[i].version->funcs->set_clockgating_state(
+			(void *)adev, state);
+		if (r)
+			DRM_ERROR("set_clockgating_state of IP block <%s> failed %d\n",
+				  adev->ip_blocks[i].version->funcs->name, r);
 	}
 	return r;
 }
···
 	for (i = 0; i < adev->num_ip_blocks; i++) {
 		if (!adev->ip_blocks[i].status.valid)
 			continue;
-		if (adev->ip_blocks[i].version->type == block_type) {
-			r = adev->ip_blocks[i].version->funcs->set_powergating_state((void *)adev,
-										     state);
-			if (r)
-				return r;
-			break;
-		}
+		if (adev->ip_blocks[i].version->type != block_type)
+			continue;
+		if (!adev->ip_blocks[i].version->funcs->set_powergating_state)
+			continue;
+		r = adev->ip_blocks[i].version->funcs->set_powergating_state(
+			(void *)adev, state);
+		if (r)
+			DRM_ERROR("set_powergating_state of IP block <%s> failed %d\n",
+				  adev->ip_blocks[i].version->funcs->name, r);
 	}
 	return r;
 }