دوستان ممنون از توجهتون
من توی سایت ubuntuforums.org سوالم رو مطرح کردم و جوابم رو گرفتم. راه حل رو هم اینجا میذارم که امیدوارم این تاپیک هم به درد یه بنده خدایی بخوره و اوبونتو رو ترک نکنه ...
لپ تاپ من Lenovo ideapad Y450 هست و گرافیکش هم Intel هست و مشکلش این بود که با کلید Fn نور صفحه اش کم و زیاد نمی شد ...
برای حل این مشکل این مطلب رو بخونید :
type in a terminal:
sudo gedit /etc/rc.local
and there you will see at the very most bottom a red colored EXIT. Just above that "exit" type the command
setpci -s 00:02.0 F4.B=00
and save the settings. Next file you will have to edit is your Grub config file. Type into a terminal
sudo gedit /etc/default/grub
there you will see different settings. Now look for the line that looks like this: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and add "acpi_osi=Linux" at the end so that the line looks like this after editing:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"
this should fix your problem. the only thing that got BROKEN is the indicator app that shows you that "bar" of the brighntess and that it is reversed (UP arrow increses brightness and DOWN decreses the brightness). But this is a price i gladly pay to change the brightness.
If you do not want to make those "permanent" changes, you can also just adjust it by command with
sudo setpci -s 00:02.0 F4.B=XX
where in XX you replace it with HEX code (reaching from 00 = 0 (brightest) to FF = 255 (darkest))