LCD brightness capability question

[David Zeuthen]

On Tue, 2006-04-18 at 12:58 +0200, Danny Kukawka wrote:
> No, it's not good to commit. 

Right.

> I assume he use the generic ACPI video driver (modprobe video) and not a 
> special driver e.g. from/for futjisu. 
> 
> 1.) I can't see where you check if this machine is a) a FujitsuSiemens or/and 
> b) this special machine in your patch. If this patch go in, HAL offer set 
> brightness for all machines with loaded video module and which have this path 
> in /proc/acpi. But this happens also on several (in fact many) other machines 
> - on this point we are at:
> 
> 2.) I see no check if the device really support set brightness. You need to 
> check if there are values returned which make sense (e.g. not <not 
> supported> )
> 
> 3.) Also if the device not return <not supported>: this mean not that set 
> brightness is supported by this machine. This can also differ in several 
> cases from bios version to bios version. And on many (maybe the most) this 
> does not work.
> 
> 4.) Also if a device support set brightness via this path the number of 
> brightness levels can differ from '8'.

I think what we need to do here is to add code to handle the generic
ACPI video in hald/linux2/acpi.c and then possibly use fdi files to say
if it's supported on a particular model or not. 

If "<not supported>" is returned do we have evidence that it always
works? If this is not the case we need a white list (e.g. need fdi
files).

For automatically loading of the appropriate kernel module, that's a
task for udev, not hal.

> You see it make no sense to commit this in the CVS.

Agreed.

    David