Laptop backlight not turning off...

Jules · External Since: Apr 28, 2004 Posts: 122

I'm going through the process of getting Slackware set up on a Dell
Inspiron 2200 at the moment.

One thing I've found is that the backlight refuses to turn off; after a
certain amount of time the display will blank, but it seems that the
backlight never switches itself off (even with the lid closed).

I'm not entirely sure which part of Linux should be responsible for this
(ACPI, X Windows, or something else), or even if it's a Linux problem at
all (i.e. is it Linux's responsibility to disable the backlight when the
lid's closed or after a certain period of inactivity - or is that entirely
a hardware thing?)

The 'change brightness' key combination for the laptop (Fn and up/down
cursor) does work, but it doesn't allow me to turn the backlight off
completely (but does at least suggest that low-level software access to
the backlight hardware is working!)

Any pointers as to how to set it up how I want? (I'm still thinking about
suspend/hibernate options, but at the very least I'd like the backlight to
go off when the lid's closed!)

System is Slackware 11, kernel updated to 2.6.18.3 (ACPI enabled), Xorg
6.9.0 and the video chipset's an Intel 915GM.

cheers

Jules

--
we've fallen off the silly boat into a sea of ridiculousness!

Unruh · External Since: May 27, 2005 Posts: 2192

Jules <julesrichardsonuk.TakeThisOut@remove.this.yahoo.co.uk> writes:

>I'm going through the process of getting Slackware set up on a Dell
>Inspiron 2200 at the moment.

>One thing I've found is that the backlight refuses to turn off; after a
>certain amount of time the display will blank, but it seems that the
>backlight never switches itself off (even with the lid closed).

>I'm not entirely sure which part of Linux should be responsible for this
>(ACPI, X Windows, or something else), or even if it's a Linux problem at
>all (i.e. is it Linux's responsibility to disable the backlight when the
>lid's closed or after a certain period of inactivity - or is that entirely
>a hardware thing?)

Nothing in Linux controls this. This is hardware.

>The 'change brightness' key combination for the laptop (Fn and up/down
>cursor) does work, but it doesn't allow me to turn the backlight off
>completely (but does at least suggest that low-level software access to
>the backlight hardware is working!)

>Any pointers as to how to set it up how I want? (I'm still thinking about
>suspend/hibernate options, but at the very least I'd like the backlight to
>go off when the lid's closed!)

>System is Slackware 11, kernel updated to 2.6.18.3 (ACPI enabled), Xorg
>6.9.0 and the video chipset's an Intel 915GM.

>cheers

>Jules

>--
>we've fallen off the silly boat into a sea of ridiculousness!

Jerry Peters · External Since: Apr 06, 2004 Posts: 80

Jules <julesrichardsonuk RemoveThis @remove.this.yahoo.co.uk> wrote:
>
> I'm going through the process of getting Slackware set up on a Dell
> Inspiron 2200 at the moment.
>
> One thing I've found is that the backlight refuses to turn off; after a
> certain amount of time the display will blank, but it seems that the
> backlight never switches itself off (even with the lid closed).
>
> I'm not entirely sure which part of Linux should be responsible for this
> (ACPI, X Windows, or something else), or even if it's a Linux problem at
> all (i.e. is it Linux's responsibility to disable the backlight when the
> lid's closed or after a certain period of inactivity - or is that entirely
> a hardware thing?)
>
> The 'change brightness' key combination for the laptop (Fn and up/down
> cursor) does work, but it doesn't allow me to turn the backlight off
> completely (but does at least suggest that low-level software access to
> the backlight hardware is working!)
>
> Any pointers as to how to set it up how I want? (I'm still thinking about
> suspend/hibernate options, but at the very least I'd like the backlight to
> go off when the lid's closed!)
>
> System is Slackware 11, kernel updated to 2.6.18.3 (ACPI enabled), Xorg
> 6.9.0 and the video chipset's an Intel 915GM.
>
> cheers
>
> Jules
>
>

I have a Latitude C600. I had similiar problems turning the backlight off.
Assuming you're using X, try adding the this to the screen section of
xorg.conf:

Option "PM" # power management
# first blank the screen, then turn off backlight 1 min later
Option "BlankTime" "11" # doesn't turn off backlight
# Option "StandbyTime" "10" # doesn't turn off backlight
Option "OffTime" "12" # Turns off backlight

and
Option "DPMS"
to your monitor section.

You might also try issuing the command
xset dpms force off
from an xterm.

Jerry

Jules · External Since: Apr 28, 2004 Posts: 122

On Fri, 08 Dec 2006 21:23:05 +0000, Jerry Peters wrote:
> I have a Latitude C600. I had similiar problems turning the backlight off.
> Assuming you're using X, try adding the this to the screen section of
> xorg.conf:
> [snip]

Fantastic - that worked perfectly!

many thanks Smile

Jules

--
we've fallen off the silly boat into a sea of ridiculousness!