[hal-info] Some thinkpad panels don't use laptop_panel.brightness_in_hardware

[Matthew Garrett]

On Fri, Oct 24, 2008 at 11:16:34AM +0200, Danny Kukawka wrote:
> On Samstag, 9. August 2008, Matthew Garrett wrote:
> > Once the acpi video module is loaded, no brightness control
> > will be done in hardware on machines that implement the ACPI backlight
> > class. However, depending on kernel options, the kernel may do it
> > instead.
> 
> But this would mean we need to add laptop_panel.brightness_in_hardware=true 
> again if the kernel handles it (from the userspace view it doesn't matter if 
> the kernel or the hardware do the change, since a reaction from userspace 
> would lead to trouble if the brightness was already changed.).
> 
> Is there a way to find out (e.g. via sysfs) if the kernel handles the change?

If there's an ACPI backlight and 
/sys/module/video/parameters/brightness_switch_enabled is Y.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org