Re: [gentoo-user] Re: Backlight problems

[Grant <emailgrant@gmail.com>]

>>>> On my just-released Dell XPS 13 Ultrabook, I can control the backlight
>>>> with 'xbacklight -set 0' and 'xbacklight -set 100'.  Any other values
>>>> cause the screen to blink and flash.  The keyboard backlight shortcuts
>>>> don't work unless I map them to xbacklight 0 and 100.  Also xbacklight
>>>> doesn't work at all if I'm unplugged from AC.  I've tried
>>>> acpi_osi=Linux and acpi_backlight=vendor in grub.conf.  acpi_osi
>>>> doesn't seem to make any difference and xbacklight doesn't work at all
>>>> without acpi_backlight.  Do I just need to wait for a newer kernel?
>>>
>>> Does the gentoo install CD or a rescue CD give you any way to test the
>>> same backlight functions?  If the backlight works correctly when running
>>> such a CD then listing the loaded kernel modules might give you a clue.
>>
>> I tried the latest Kubuntu and Ubuntu LiveCDs via unetbootin but the
>> backlight behavior is the same as with Gentoo.  Please let me know if
>> anyone has any ideas on this.
>>
>> - Grant
>>
>
> Grant,
>   Sorry I missed this thread earlier. I've got an Asus 17" laptop
> that I've been trying unsuccessfully to get the keyboard backlighting
> to work correctly for weeks (maybe months - I no longer remember how
> long) On my machine I get keyboard backlighting when I boot the
> machine, but if I turn off the lights with the switch on the machine I
> cannot so far turn them back on by any means.
>
>   On this machine xbacklight -get responds that nothing has backlight
> properties so I've clearly got some configuration issues.
>
>   As for the kernel I'm using vanilla-sources-3.2.10 so I don't think
> there's a lot that is newer than that.
>
>   I don't care much about screen backlighting but keyboard
> backlighting is important to me.
>
> - Mark

Hey Mark, I'm happy to say I just fixed the screen backlighting on my
system, but I'm sorry to say I don't think it will help you with
keyboard backlighting.  To fix it, I removed 'acpi_backlight=vendor'
from grub and added 'echo 0 >
/sys/class/backlight/intel_backlight/brightness' to
/etc/local.d/backlight.start and made that file executable.  Now
backlight control works perfectly via the keyboard shortcuts with no
other configuration and no xbacklight.  I'm on
hardened-sources-3.2.2-r1.

BTW, I noticed baselayout1.start and baselayout1.stop are no longer
created in /etc/local.d.

- Grant