Packard Bell EasyNote LV need i915.invert_brightness=1

[Daniel Vetter]

On Wed, Jun 26, 2013 at 01:30:01PM +0200, Petter Reinholdtsen wrote:
> [Daniel Vetter]
> > Nah, silence just means that your patch fell through the crack while I've
> > travelled around a bit. Thanks for poking, it's merged now for 3.11 (with
> > cc: stable) to my drm-intel-next-queued branch. I've slightly bikeshedded
> > the patch though for formatting.
> 
> Right.  Thank you.
> 
> Btw, a related question.  On the laptop in question, even when I use
> i915.invert_brightness=1, the kernel still seem to be confused about the
> brightness values.  This causes the KDE system powerdevil to turn off
> the screen when I log into KDE.
> <URL: https://bugs.kde.org/show_bug.cgi?id=321580 > got some details
> about the problem, which can be seen from this shell run:
> 
>   % for interface in /sys/class/backlight/*; do echo $interface; cat $interface/max_brightness; cat $interface/actual_brightness; done
>   /sys/class/backlight/acpi_video0
>   100
>   0
>   %
> 
> The max_brightness value is 100, and the current brightness is 0, which
> actually is full brightness (and not black screen).  This fools
> powerdevil into turning off the screen while believing it turn it on.
> 
> Should not the ACPI backlight system also know about the inverted
> brightness setting, and adjust the /sys/ interface to get these values
> to behave consistently across all hardware models?
> 
> Is there some other quirk table for acpi that also need to be updated?

If the acpi brightness controller is broken, it needs to be quirked away.
For that please file a bug report against the ACPI subsystem. With that
done the automagic fallback rules of the intel DDX driver should expose
the "right" backlight interface through the backlight xrandr property. If
KDE's powerdevil isn't using that one (and frobs around with the backlight
controllers directly) that'd be a bug in kde.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch