Some background info: Thinkpad X230 uses PWM to control screen brightness. The default frequency is 220 Hz which is too low and causes eye strain. By default, PWM is disabled only when you set the screen brightness to maximum. But it is not practical to always set the brightness to max when using the laptop.
Problem: Since this is a well known problem, there exists a solution both on Linux (apparently) and Windows to increase the PWM frequency without increasing the brightness. I use this tool on Windows to increase the frequency irrespective of the brightness level, and it works. But on Antergos, I am following this and this to increase the frequency. As soon as I try to increase the frequency with this command [intel_reg write 0xC8254 <value>], the brightness also increases. I do not want the increase in frequency to cause an increase in brightness level, just like on Windows. How do I do it?