Some PCs still turn off the backlight by zero brightness even when the maximum brightness level is less than 100.
Submitted by Shih-Yuan Lee (FourDollars)
The minimum brightness of the laptop screen panel may not be realistic sometimes especially when having a problematic screen panel.
For example, Dell Precision 5720 AIO only has 9 levels in /sys/class/backlight/intel_backlight/max_brightness because the wrong settings in VBIOS. It is an all-in-one desktop PC and there is no brightness hotkey to control the backlight. When we set 0 to /sys/class/backlight/intel_backlight/brightness, it turns off the panel's backlight and there is no way to brightness up the backlight again so we can only avoid using 0 as the minimum backlight level.