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I have a HP Pavilion g6 laptop. After installing Ubuntu, screen brightness does not not decrease. Due to this high brightness, I am unable to use Ubuntu properly.

Graphics- ATI Radeon.

Please help me solve the problem.

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By "does not decrease", do you mean brightness change via fn keys of your laptop or do you mean via Ubuntu's system brightness settings? –  FuzzyQ Aug 11 '12 at 17:48
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2 Answers 2

A friend of mine had the exact same problem on a Samsung NP530 laptop, after an Ubuntu 12.04 kernel update.

/etc/default/grub, GRUB_CMDLINE_LINUX_DEFAULT variable, he added acpi_osi=

After running update-grub and a reboot, problem solved.

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Try setting acpi_backlight=vendor upon start. I've had to do that for two laptops, an ASUS and a Dell in order to make the backlight work.

Add to the variable GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub, acpi_backlight=vendor. Then run update-grub and reboot.

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