SUMMARY When I click the battery and brightness icon, and adjust the brightness, it goes all the way down to 0% and I can't see anything! STEPS TO REPRODUCE 1. Click battery and brightness icon in the taskbar 2. Drag brightness slider all the way down to the lowest setting (0%) OBSERVED RESULT Backlight is now off, and it is now impossible to see anything unless you have light theme enabled and shine a torch directly at the screen. EXPECTED RESULT Backlight should remain on at least 1% brightness. SOFTWARE/OS VERSIONS Linux/KDE Plasma: (available in About System) KDE Plasma Version: 5.24.5 KDE Frameworks Version: 5.94.0 Qt Version: 5.15.4 ADDITIONAL INFORMATION Kernel: 5.18.1-zen1-1-zen x86_64 CPU: Intel Core i7-10750H GPU: Intel Corporation CometLake-H GT2 [UHD Graphics] (rev 05) Display server: X11 Backlight: /sys/class/backlight/intel_backlight
You're talking about the System Tray applet, right? In there, the slider does go down to 0%, but internally it's actually setting the backlight value to 1, not 0. This would suggest that your display hardware turns off the backlight at a value above 0, which is unfortunate. Sadly this isn't standardized at all.
(In reply to Nate Graham from comment #1) > You're talking about the System Tray applet, right? In there, the slider > does go down to 0%, but internally it's actually setting the backlight value > to 1, not 0. This would suggest that your display hardware turns off the > backlight at a value above 0, which is unfortunate. Sadly this isn't > standardized at all. Yes, the system tray applet for battery and brightness. Why not just limit the slider to 1-100%? 1% is barely visible at all in daylight but perfect for using my computer in complete darkness.
> Yes, the system tray applet for battery and brightness. Why not just limit the slider to 1-100%? >> In there, the slider does go down to 0%, but internally it's actually setting the backlight value to 1%, not 0%. It already does exactly that. Seems like your hardware treats that 1% as a signal to turn the screen completely off. Please, test your setup more and tell us what's the lowest limit when the screen is not turned off yet. You may write raw values to sysfs backlight 'files', use xbacklight or whatever the tool you are using.
Indeed, I would be interested in knowing that as well. Turning off the backlight at nonzero brightness values is very odd behavior from the hardware.
/sys/class/backlight/intel_backlight/brightness: 232 sets the backlight to the lowest level without switching it off. 231 switches it off completely. max_brightness is 120000.
Both values are slightly below the 2% threshold: 0,019(3) vs. 0,01925. I guess we could bump the minimum brightness to 2% then.
This has since been fixed by a change in the Intel GPU driver.