Brightness key not working Ubuntu 16.04 LTS - Exactly same problem as me, except my laptop is Lenovo IdeaPad P400 touch. Can't change brightness in Ubuntu 16.04 LTS - Tried both the solution given by @Archisman Panigrahi and by @Serge Stroobandt. Ubuntu 14.04 brightness problem (Lenovo Z500) - tried solution given by @Lorenzo Gabriele. Hi I have a Lenovo ideapad P400 Touch laptop that I just bought back in April with Windows 8 on it. And about a month ago I upgraded it to the Windows 8.1 preview. Last night I was messing with the brightness and I took it down to the lowest it can get, and then when I tried to move the slider back up to make my screen brighter the slider moved but my screen stayed on dim. Dim screen on Windows 10. I'm using a Lenovo IdeaPad Z400. I tried to update drivers but Lenovo hasn't released any updates for Windows 10. Can anybody please help? Problem is, the driver doesn't work perfectly, so it would raise brightness to the maximum and it'd be stuck there. If I tried to lower it, it would drop to min and I'd have. May 15, 2017 Lenovo ideapad P400, dimmed screen, can't change brightness with Windows 10 Upgraded my Lenovo ideapad P400 to Windows 10, got dimmed screen, can't change backlight brightness, tried: 1. Adaptive display turned off, still stuck with dimmed display. (I had to mod-BIOS to get Intel 7260 AC card to work). I've been a pretty disappointed with.
FOR 12.10Okay, I found an answer in web page.This resolved my brightness difficulties permanently: sudo gedit /étc/default/grubYou wiIl discover this collection in the brand-new opened home window: GRUBCMDLINELINUXDEFAULT='quiet splash'Change it to: GRUBCMDLINELINUXDEFAULT='calm little acpibacklight=seller'Save and close up the windowpane and type this in the port: sudo update-grubánd reboot. FOR 13.04.
Add the acpibacklight=seller to your grub default control line. Run the update-grub order. blacklist the ideapadlaptop by incorporating 'blacklist ideapadlaptop' tó your /etc/modprobé.m/blacklist.conf file. Sins of a solar empire distant stars mod.
Reboot.