Screen brightness does not change on Toshiba Satellite in Karmic

[deibhaid]

**************************************************
brightness_up.sh
**************************************************
#!/bin/sh
test -f /tmp/dim || echo ff > /tmp/dim
brightness=$((`cat /tmp/dim`))
if [ $(grep -c ff /tmp/dim) -eq 1 ] ; then
setpci -s 00:02.0 F4.B=ff;exit;
elif [ $brightness -gt 99 ] ; then
brightness=ff;
else brightness=$((`cat /tmp/dim`+5));
fi
export brightness
if [ $brightness -eq 100 ] ; then
brightness=ff;
fi
echo $brightness > /tmp/dim
setpci -s 00:02.0 F4.B=`cat /tmp/dim`

**************************************************
brightness_down.sh
**************************************************
#!/bin/sh
test -f /tmp/dim || echo 6 > /tmp/dim
brightness=$((`cat /tmp/dim`-5))
if [ $(grep -c ff /tmp/dim) -eq 1 ] ; then
brightness=95;
elif [ $brightness -lt 0 ] ; then
brightness=0;

fi
echo $brightness > /tmp/dim
export brightness
setpci -s 00:02.0 F4.B=`cat /tmp/dim`

[deibhaid]

It looks like a rather ugly script, so if someone has suggestions or modifications, feel free to add them!

[squee]

running 11.04b and by default this still isnt resolved. I'd prefer not to use a script like before. The function button works fine as always, and the notification comes up indicating that the screen is brighter or dimmer but it doesnt change.

Any ideas? (also can a mod unmark this a solved - it is not.)

[wgarciamachmar]

Same problem here. Did the script. Nothing changes, though the indicator shows up and hot keys are working.

[squee]

Months later I have found a partial solution.

The below tutorial changes the brightness depending on the state of the AC charger. It works perfectly for me (though I modified the script so the AC brightness was at max FF rather than 99 value)
http://forums.linuxmint.com/viewtopic.php?f=42&t=63446
http://ubuntuforums.org/showpost.php...0&postcount=26

also for manual changing outside of the above script, one can use

sudo setpci -s 00:02.0 F4.B=FF

Where FF can be replaced with any value from 00 (black) to FF max bright using hexadecimal notation.

Hope this helps!

[RSA-2010]

I had tried getting this to work on a few occasions previously, even to the point of getting into the deeper innards here:

https://wiki.ubuntu.com/Kernel/Debugging/Backlight

. . . but all to no avail . . . I had simply gotten used to having a full-on backlight and the related crappier battery life, which was an everpresent reminder of things not being perfect.

However, in Kubuntu 11.10 (upgraded from 11.04 and possibly from 10.10 further back) on a Toshiba Satellite T135-S1310, adding "nomodeset acpi_backlight=vendor" to the GRUB_CMDLINE_LINUX_DEFAULT line did not work (as expected, and as noted previously in the thread, nomodeset just freaked everything out), but removing nomodeset and just leaving the vendor part has at last worked perfectly. The Fn keys work and it can all be changed in the software settings.

Specifically, my line looks like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

And my my, what an amazing change!

I don't know of any other special events which might've occurred, so if others try this and have an issue please let me know.

[ccurry21]

RSA-2010's solution does not work for me. After adding this line and rebooting, brightness hotkeys work as before until I suspend, but when awakening the machine the backlight remains completely dimmed.

[zampes]

Hi there,
I'm in the same fix right now, with a brand new Toshiba L755-s5242GR. Has anyone found anything that would allow one to dim the backlight? I'm going blind here. I've tried all the fixes mentioned here and nothing works; I've tried some other things myself, but still, no fix.

[RSA-2010]

As it happens, I developed an issue where the laptop wouldn't go to sleep. The backlight=vendor thing is the cause.

Now in Kubuntu 12.04, removing the backlight line returns the unit to its old behavior (sleeps, but always has full brightness), so the problem is not really solved.

Putting that line in produces brightness change capability, but if I have to walk away from the laptop with the lid open it will sit there like an idiot until the battery drains completely.

Closing the lid can produce the desired sleep *sometimes*, and of course manually ordering to sleep via the "Leave" widget or similar will work, but it will wake up and drain itself if the battery gets low (which is just stellar behavior when it's in a case, lemme tell ya).

So, basically, it's a compromise right now between being blind in a dark room or letting the laptop drain itself and lose work if I have to run fast and don't get a chance to close the lid and confirm it actually decided to sleep this time.

[nomnex]

So, basically, it's a compromise right now between being blind in a dark room or letting the laptop drain itself and lose work if I have to run fast and don't get a chance to close the lid and confirm it actually decided to sleep this time.

If you need the ACPI feature on your notebook, you should still be able to set a default brightness when you enter the BIOS setting. Try that: enter a TTY console, see if the keys work, or when you boot: enter the BIOS menu (usually ALT+F2) and try the keys.