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Devastator

Member

From: Poland

Registered: 2008-05-27

Posts: 179

Backlight buttons change incorrect value

Hi, I have recently encountered a weird issue with the backlight buttons on my Toshiba Satellite A500:

the backlight buttons are not changing the screen brightness, but they DO change a value of /sys/class/backlight/toshiba/brightness (which have no effect to the real screen brightness). However, I have another entry in /sys/class/backlight - acpi_video0. And changing brightness value in this directory DO change the real screen brightness.

Anybody know how may I fix that?

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Inxsible

Forum Fellow

From: Chicago

Registered: 2008-06-09

Posts: 9,183

Re: Backlight buttons change incorrect value

Aargh !

There was a thread started about the same issue. Please search the forums before posting.
Have you seen this thread? If so, has the solution worked? If not what else have you tried?

https://bbs.archlinux.org/viewtopic.php?id=143628

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Devastator

Member

From: Poland

Registered: 2008-05-27

Posts: 179

Re: Backlight buttons change incorrect value

I have seen this thread before, as well as several others. Nothing helped.

Of course I may use a dirty hack, and map Brightness Buttons directly to script that will handle backlight properly, but I think it may be solved in a more proper way.

(I am currently grepping the config files in a search for 'backlight' or 'brightness'. This should be set somewhere...)

About what I tried:
full system update + reboot
reinstall systemd-tools + reboot,
mkinitcpio -p linux (I don't remember if that was the exact command, but it was mentioned somewhere)

More details:
Nvidia graphics,
I don't use laptop-mode-tools, but I have seen, that it may control backlight, and even have a setting for selecting a proper location of brightness' "file"

EDIT:
(nothing interesting found by grep in /etc nor in /usr/lib... any suggestions?)

Last edited by Devastator (2012-06-19 19:19:54)

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Some applications are WYSIWYG, and some are WYSIWTF.

Devastator

Member

From: Poland

Registered: 2008-05-27

Posts: 179

Re: Backlight buttons change incorrect value

Okay, I have temporarily patched that using scripts+keybindings in XFCE4. But still - I think that the reaction to backlight buttons should be configurable somewhere. I have grepped most of my system, and found nothing. Perhaps it is some magic/undocumented setting? Or latest NVidia drivers fault?

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MadCat_X

Member

Registered: 2009-10-08

Posts: 189

Re: Backlight buttons change incorrect value

I managed to "fix" this by commenting out the part of the toshiba_acpi driver which registers the "toshiba" backlight device. I wonder what has changed in the driver, the git history doesn't seem to reveal anything...