Packard Bell EasyNote LV need i915.invert_brightness=1

[Daniel Vetter]

On Thu, Jun 27, 2013 at 05:05:44PM +0200, Petter Reinholdtsen wrote:
> [Daniel Vetter]
> > The buttons might do something fancy behind the scenes (kernel or
> > userspace), so can you please also check whether directly changing
> > the backlight values in /sys/class/backlight works correctly?
> 
> There is full brightness when I set the value of max_brightness into
> the brightness file (as in 'echo 4882 > brightness'), and complete
> darkness when it is set to 0.  This was using acpi_backlight=vendor.
> I suspect that mean the intel_backlight driver is working correctly,
> but am not sure if 0 is supposed to be completely dark or not.

Ok, so the intel backlight actually seems to work here and we only have a
funny interaction between the acpi backlight and the intel backlight. I'll
drop your patch to invert the i915 backlight brightness again.

> > acpi can't invert, and the different backlight drivers can affect
> > each another in funny ways. Which is way we have a clearly defined
> > priority order that userspace should use, and then _only_ touch the
> > selected backlight. ACPI wins over i915, so if the ACPI backlight is
> > broken (but the raw i915 backlight driver works) we need to
> > blacklist it.
> 
> Right.  I guess my findings above mean the hardware should be
> blacklisted (from acpi?).

Sounds like. Please file a bug report against ACPI -> Video on
bugzilla.kernel.org.
> 
> Is there no way to discover using ACPI if the backlight brightness
> setting should be inverted or not?

Afai we know, not.

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