mei_cl_read_start
rets = mei_cl_read_start(cl, length, NULL);
mei_cl_read_start(cldev->cl, mei_cl_mtu(cldev->cl), NULL);
ret = mei_cl_read_start(cldev->cl, mei_cl_mtu(cldev->cl), NULL);
int mei_cl_read_start(struct mei_cl *cl, size_t length, const struct file *fp);
rets = mei_cl_read_start(cl, length, file);
mei_cl_read_start(cl, mei_cl_mtu(cl), file);