[hal-info] Dell laptops control brightness in hardware

[Larry]

Michael E Brown wrote:
> On Thu, Nov 15, 2007 at 12:11:08AM +0000, Rui Tiago Matos wrote:
>   
>> [cross posting to a dell list so that the relevant people can provide
>> more insight]
>>
>> On 14/11/2007, Martin Pitt <martin at piware.de> wrote:
>>     
>>> hi Rui,
>>>       
>> Hi!
>>
>>     
>>> Rui Tiago Matos [2007-11-14 19:37 +0000]:
>>>       
>>>> Besides, doesn't the existence of the dell backlight addon make it
>>>> software controlled?
>>>>         
>>> You can't, it's hardwired (as Danny pointed out already). AFAIUI, the
>>> file you pointed out just tells hal that it uses the Dell specific
>>> backend for brightness control, which I guess will just read out the
>>> new brightness without actually trying to set it. (I might be wrong
>>> here, I don't know much about the Dell perculiarity).
>>>       
>> Well, I have a Latitude D630 running Fedora 8 and currently this is
>> how it works:
>>
>> 1. the dcdbas module has got to be loaded before hal starts so that
>> the dell addon is loaded by hal. I've put it in the initrd (ugly hack
>> but it works. Matt Domsch had done the right fix for it, see [1]).
>>
>> 2. gnome power manager is able to change the brightness on software
>> using said dell addon which uses dell's libsmbios. The libsmbios CLI
>> tools can also set the brightness (i.e. dellLcdBrightness).
>>
>> 3. what doesn't work right (see [2]) is notification from the hardware
>> (or BIOS?) --> hal when one uses the keys.
>>     
>
> The brightness control keys produce a key scancode which can be mapped
> to tell HAL what is going on. I havent looked into this myself. I think
> ubuntu does something like this, as I saw a similar inquiry a few days
> ago on ubunutu.
> --
> Michael
>
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>   
/usr/bin/lshal -m  shows info such as
11:19:43.630: platform_i8042_i8042_KBD_port_logicaldev_input condition 
ButtonPressed = brightness-up
11:19:43.654: platform_i8042_i8042_KBD_port_logicaldev_input condition 
ButtonPressed = brightness-up

in in my Kubuntu-Gutsy  7.10 on an Inspirion E1505 purchase before 
Ubuntu install was available from Dell.   I must have installed some 
utility or configuration program because now pressing Fn+Up or Fn+Down 
brings up a window with a progress bar and allows changing of the 
display brightness.

FYI, I'm  too much of a novice to understand why I can now change the 
display brightness. Hopefully this will help someone else.

Larry