Cannot change brightness / gamma on Toshiba Satellite

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Cannot change brightness / gamma on Toshiba Satellite

Postby CountCarrion » 2017-03-19 20:40

Hello,
I have a Toshiba Satellite C70D-A-114. It came with Windows 8, but very poor performance lead me to install Debian which has performed much smoother.
Unfortunately, none of the special function keys work after installing Debian. This creates a problem as the laptop being on 100% brightness makes it extremely uncomfortable to use, and I have no way of lowering it.

I have looked at a few solutions but can't seem to make any headway.
xrandr returns "failed to get size of gamma for output default" and /etc/default/grub contains the line 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"'.
I have tried changing 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"' to 'GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" but it seemed to have no effect.'

If anyone might have a solution, please suggest it; I'd love to get this fixed.

Thank you.
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Re: Cannot change brightness / gamma on Toshiba Satellite

Postby Head_on_a_Stick » 2017-03-19 21:19

CountCarrion wrote:I have tried changing 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"' to 'GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" but it seemed to have no effect.'

Did you remember to update your GRUB configuration?

This will list the currently applied parameters:
Code: Select all
cat /proc/cmdline

You may be able to adjust the level manually — check for any folders under /sys/class/backlight for the relevant files.
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Re: Cannot change brightness / gamma on Toshiba Satellite

Postby stevepusser » 2017-03-19 21:37

Do you have the firmware for your AMD graphics installed?

https://wiki.debian.org/AtiHowTo

If that doesn't have any effect, you could give the proprietary driver a try.
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Re: Cannot change brightness / gamma on Toshiba Satellite

Postby phenest » 2017-03-19 21:59

CountCarrion wrote:I have tried changing 'GRUB_CMDLINE_LINUX_DEFAULT="quiet"' to 'GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" but it seemed to have no effect.'

Try "acpi_backlight=video". That worked for me.
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