[gentoo-user] How to dim the display brightness

[gentoo-user] How to dim the display brightness

[Damian]

Hi,

I cannot find the way to dim the brightness of the display on my
laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
can find anything in google.

I would like the brightness of the screen to be dimmed when the
computer is idle for a certain amount of time. Do you have any clues
where I can start digging?

Thanks in advance,
Damian.

Re: [gentoo-user] How to dim the display brightness

[Antonio Quartulli]

Damian ha scritto:
> Hi,
> 
> I cannot find the way to dim the brightness of the display on my
> laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
> can find anything in google.
> 
> I would like the brightness of the screen to be dimmed when the
> computer is idle for a certain amount of time. Do you have any clues
> where I can start digging?
> 
> Thanks in advance,
> Damian.
> 
> 
It depends on your video driver. First of all, which video card have you
got?

-- 
Antonio Quartulli <http://www.ritirata.org/ordex>

Re: [gentoo-user] How to dim the display brightness

[Sebastian Günther]

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* Damian (damian.only@gmail.com) [23.02.09 10:19]:
> Hi,
> 
> I cannot find the way to dim the brightness of the display on my
> laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
> can find anything in google.
> 
Did you enable the apropiate acpi drivers in the kernel? They depend on 
your laptop model...

> I would like the brightness of the screen to be dimmed when the
> computer is idle for a certain amount of time. Do you have any clues
> where I can start digging?

http://www.gentoo.org/doc/en/power-management-guide.xml

> 
> Thanks in advance,
> Damian.
> 

HTH
Sebastian

-- 
 " Religion ist das Opium des Volkes. "      Karl Marx

 SEB@STI@N GÜNTHER         mailto:samson@guenther-roetgen.de

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Re: [gentoo-user] How to dim the display brightness

[Damian]

On Mon, Feb 23, 2009 at 12:41 PM, Antonio Quartulli <ordex@ritirata.org> wrote:
> Damian ha scritto:
>> Hi,
>>
>> I cannot find the way to dim the brightness of the display on my
>> laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
>> can find anything in google.
>>
>> I would like the brightness of the screen to be dimmed when the
>> computer is idle for a certain amount of time. Do you have any clues
>> where I can start digging?
>>
>> Thanks in advance,
>> Damian.
>>
>>
> It depends on your video driver. First of all, which video card have you
> got?
Indeed. I have an Nvidia Quadro. Sorry for not specifying that.

My laptop is a Compaq 8510w.

> --
> Antonio Quartulli <http://www.ritirata.org/ordex>
>
>

Re: [gentoo-user] How to dim the display brightness

[Damian]

On Mon, Feb 23, 2009 at 1:03 PM, Sebastian Günther
<samson@guenther-roetgen.de> wrote:
> * Damian (damian.only@gmail.com) [23.02.09 10:19]:
>> Hi,
>>
>> I cannot find the way to dim the brightness of the display on my
>> laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
>> can find anything in google.
>>
> Did you enable the apropiate acpi drivers in the kernel? They depend on
> your laptop model...
Yes. But nothing seems to work.

I can do it by using nvidia settings, but the dimming is different
from the one you get when pressing Fn + the dimming keys on a text
console (btw, this is a weird behavior: I cannot do key-based dimming
when X is running).

> http://www.gentoo.org/doc/en/power-management-guide.xml
Yep, I looked there, but the example don't apply to my laptop model :(

Thanks.

Re: [gentoo-user] How to dim the display brightness

[Sebastian Günther]

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* Damian (damian.only@gmail.com) [23.02.09 19:21]:
> On Mon, Feb 23, 2009 at 1:03 PM, Sebastian Günther
> <samson@guenther-roetgen.de> wrote:
> > * Damian (damian.only@gmail.com) [23.02.09 10:19]:
> >> Hi,
> >>
> >> I cannot find the way to dim the brightness of the display on my
> >> laptop. It doesn't seem to be nothing useful in /proc/acpi neither I
> >> can find anything in google.
> >>
> > Did you enable the apropiate acpi drivers in the kernel? They depend on
> > your laptop model...
> Yes. But nothing seems to work.
> 
acpi_os-name = "Linux" as kernel parameter might help.

and take a look if /sys/class/backlight/acpi_video0/ is present:
this is the kernel interface to set the brightness.

CONFIG_BACKLIGHT_LCD_SUPPORT

is the appropriate kernel config category to look at in recent kernels.

BTW which kernel are you using?

> I can do it by using nvidia settings, but the dimming is different
> from the one you get when pressing Fn + the dimming keys on a text
> console 
No doubt: the first dimms the videocard output, the latter the LCD.

>(btw, this is a weird behavior: I cannot do key-based dimming
> when X is running).

I think that the Xserver catches this before reaching the hardware.

You can use xev to see which keycode is emmitted and then look in your 
desktop environment if this is match with some action.

> 
> > http://www.gentoo.org/doc/en/power-management-guide.xml
> Yep, I looked there, but the example don't apply to my laptop model :(
> 
Well. it should be somehow applicable, because it is rather generic.

> Thanks.
> 

HTH
Sebastian

-- 
 " Religion ist das Opium des Volkes. "      Karl Marx

 SEB@STI@N GÜNTHER         mailto:samson@guenther-roetgen.de

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Re: [gentoo-user] How to dim the display brightness

[Damian]

Hi Sebastian,

> acpi_os-name = "Linux" as kernel parameter might help.
Ok, I've changed the grub menu.lst file. After the reboot I will write
if something changes.

>
> and take a look if /sys/class/backlight/acpi_video0/ is present:
> this is the kernel interface to set the brightness.
I have it, but running
    cho 2 > /sys/class/backlight/acpi_video0/brightness
has no effect in the display brightness.

> CONFIG_BACKLIGHT_LCD_SUPPORT
>
> is the appropriate kernel config category to look at in recent kernels.
Yes, that variable is set.

> BTW which kernel are you using?
2.6.27-r2

> No doubt: the first dimms the videocard output, the latter the LCD.
I didn't know the reasons for this "missmatch", thanks a lot for this
brief but useful explanation.

> You can use xev to see which keycode is emmitted and then look in your
> desktop environment if this is match with some action.
In fact, Fn + dimming keys produces output. Now, to do something
useful, I need to know how to dim the light of the LCD.

> Well. it should be somehow applicable, because it is rather generic.
I don't know how to replace this line
    echo "level ${LEVEL}" > /proc/acpi/ibm/brightness

I have a file
    /proc/acpi/video/C14B/C160/brightness
whose contents look like
    levels:  100 51 30 37 44 51 58 65 72 79 86 93 100
    current: 72

I did some echoes to that file, but no luck so far :(

Re: [gentoo-user] How to dim the display brightness

[Damian]

On Mon, Feb 23, 2009 at 9:57 PM, Damian <damian.only@gmail.com> wrote:
> Hi Sebastian,
>
>> acpi_os-name = "Linux" as kernel parameter might help.
> Ok, I've changed the grub menu.lst file. After the reboot I will write
> if something changes.
Nope :(

>>
>> and take a look if /sys/class/backlight/acpi_video0/ is present:
>> this is the kernel interface to set the brightness.
> I have it, but running
>    cho 2 > /sys/class/backlight/acpi_video0/brightness
> has no effect in the display brightness.
>
>> CONFIG_BACKLIGHT_LCD_SUPPORT
>>
>> is the appropriate kernel config category to look at in recent kernels.
> Yes, that variable is set.
>
>> BTW which kernel are you using?
> 2.6.27-r2
>
>> No doubt: the first dimms the videocard output, the latter the LCD.
> I didn't know the reasons for this "missmatch", thanks a lot for this
> brief but useful explanation.
>
>> You can use xev to see which keycode is emmitted and then look in your
>> desktop environment if this is match with some action.
> In fact, Fn + dimming keys produces output. Now, to do something
> useful, I need to know how to dim the light of the LCD.
>
>> Well. it should be somehow applicable, because it is rather generic.
> I don't know how to replace this line
>    echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
>
> I have a file
>    /proc/acpi/video/C14B/C160/brightness
> whose contents look like
>    levels:  100 51 30 37 44 51 58 65 72 79 86 93 100
>    current: 72
>
> I did some echoes to that file, but no luck so far :(
>

Re: [gentoo-user] How to dim the display brightness

[Steffen Loos]

Hello Damian,

>>> and take a look if /sys/class/backlight/acpi_video0/ is present:
On an IBM T61 i have acpi_video1 too. Video0 represents the vga/dvi output where video1 represents the LCD.
Also have a look on max_brightness on this dirs for the maximum value. 

>>
>>> You can use xev to see which keycode is emmitted and then look in your
>>> desktop environment if this is match with some action.
>> In fact, Fn + dimming keys produces output. Now, to do something
>> useful, I need to know how to dim the light of the LCD.
As workarround you could switch to a console (Ctrl+Alt+F1) and try to dim with your fn+ keys.

>>
>>> Well. it should be somehow applicable, because it is rather generic.
>> I don't know how to replace this line
>>    echo "level ${LEVEL}" > /proc/acpi/ibm/brightness
>>
>> I have a file
>>    /proc/acpi/video/C14B/C160/brightness
>> whose contents look like
>>    levels:  100 51 30 37 44 51 58 65 72 79 86 93 100
>>    current: 72
Be careful to touch the right (video-)output. In /proc/acpi/video i have two devices: VID and VID1. VID1 references to my LCD.

Steffen

Re: [gentoo-user] How to dim the display brightness

[Damian]

Hi Steffen,

>>>> and take a look if /sys/class/backlight/acpi_video0/ is present:
> On an IBM T61 i have acpi_video1 too. Video0 represents the vga/dvi output where video1 represents the LCD.
> Also have a look on max_brightness on this dirs for the maximum value.
No, I only have video0.

> As workarround you could switch to a console (Ctrl+Alt+F1) and try to dim with your fn+ keys.
Yes, that's is what I'm currently doing.

> Be careful to touch the right (video-)output. In /proc/acpi/video i have two devices: VID and VID1. VID1 references to my LCD.
Yes, I looked into that folder, but I had no results so far :(

I'm still trying ...

Thanks for your mail.

Best regards,
Damian.

> Steffen
>
>
>
>