I recently bought a Lenovo Legion Y540, and most options work except for the brightness control keys, the computer starts with 100% brightness and the keys (F5 and F6) seemingly do nothing, the brightness pop-up also does not show up. I have found that the following command seems to work xrandr --output DP-4 --brightness 0.6 to lower the brightness. I tried setting GRUB_CMDLINE_LINUX="acpi_backlight=vendor" in the GRUB settings but that did not help things either. I did the installation with nouveau.modeset=0 and I do remember the keys to be working. Its after installing nvidia drivers that this problem seems to have risen (not absolutely sure). Any help would be appreciated.

  • I have the same problem (Y540 with nvidia drivers on Ubuntu 19.04), but for me the brightness pop-ups does show up, and the slider changes the value but the actual brightness does not change. – GuiGS Sep 2 '19 at 8:48

Setting the bios to switchable graphics works for me (y540 with gtx1650). Also setting "acpi_backlight=intel_backlight" as kernel option works but also seems to mess with resume from suspend.

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