By the way, here's what I believe is the problem. As nvidia-bl works properly with nouveau (and with the range of 0-44000), but not the offical nvidia driver, it may be a problem with the nvidia official driver, which only exposes the spectrum of brightness in [0-1023]. Then, of course, nvidia-bl still thinks it's [0-44000] because it's a Macbook 7,1, and the problem occurs.
By the way, here's what I believe is the problem. As nvidia-bl works properly with nouveau (and with the range of 0-44000), but not the offical nvidia driver, it may be a problem with the nvidia official driver, which only exposes the spectrum of brightness in [0-1023]. Then, of course, nvidia-bl still thinks it's [0-44000] because it's a Macbook 7,1, and the problem occurs.