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I have 15.10 default install, no any changes to /etc/default/grub. Now when I press Fn + arrowUp/Down I can see display brightness change notification. Moreover, /sys/class/backlight/acpi_video0/* seem to reflect my pressings and notifiaction's bar length. So, everything looks good, but display's brightness does not change at all.

When I try to put aspm_pcie=force, acpi_osi=linux, acpi_osi=vendor, acpi_brightness=vendor or some combination of theese --- nothing improves (however I can get things worse: values in /sys/class/backlight/acpi_video0/* stop to reflect my pressings).

There are other solution which says to put into xorg.conf (Device section) the line:

Option "RegistryDwords" "EnableBrightnessControl=1"

But where should I try to put this line in 15.10?

Is there any other solution so far?

brownian
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  • Is there anything other then acpi_video0 in /sys/class/backlight/? Do also check with acpi_brightness=vendor. Option "RegistryDwords" "EnableBrightnessControl=1" is for Nvidia's proprietary river. Does Dell Vostro 3700 have Nvidia graphics? What does it have? – mikewhatever Dec 18 '15 at 10:03
  • @mikewhatever, yes, there is nv_backlight, too. And yes, I did a check with acpi_brightness=vendor, it didn't make any difference. Yes, my Vostro has GeForce GT 330M, but I am not sure which driver does it use. Thank you. – brownian Dec 18 '15 at 10:59
  • @mikewhatever, *_brightness values in /sys/class/backlight/nv_backlight do not reflect my pressings (the are always the same). – brownian Dec 18 '15 at 11:01
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    I don't know the scale (0-10, or 0-100), but what happens if you change the value in /sys/class/backlight/nv_backlight/brightness? Use echo X > suso tee /sys/class/backlight/nv_backlight/brightness, where X is the value. Does the screen brightness change? – mikewhatever Dec 18 '15 at 11:03
  • @mikewhatever, yes, it does! – brownian Dec 18 '15 at 11:15
  • Then try this solution. Hope it works. – mikewhatever Dec 18 '15 at 11:24
  • @mikewhatever, I have no xorg.conf, just /usr/share/X11/xorg.conf.d/ with files, no one of which contains Device section. Shall I create new file? Where can I read about its content? – brownian Dec 18 '15 at 11:29
  • xorg.conf is not there by default. The procedure from my previous comment will create it, just paste the second block of text, then hit ctrl-o to and then ctrl-x to exit. – mikewhatever Dec 18 '15 at 11:43
  • @mikewhatever, yes, sorry. So, I have had (and have specified) nouveau video driver and nothing helped. Now everything works after apt-get install nvidia-current driver. With "clean" /etc/default/grub. With xorg.conf you've pointed me. THANK YOU. – brownian Dec 18 '15 at 12:23

1 Answers1

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I had kind of bug that I figured out recently, I don't know if is the same problem.

The button of backlight change when pressed, but it didn't affect the backlight in fact. I tried installing xbacklight and using xrandr to set the backlight and nothing.

Finally, I tried go in BIOS and change with the same button of keyboard, and(I don't know why), it works!! When I came back to ubuntu, the problem was solved.

Anderson Pimentel
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