Packard Bell EasyNote LV need i915.invert_brightness=1

[Petter Reinholdtsen]

[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.

> 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?).

Is there no way to discover using ACPI if the backlight brightness
setting should be inverted or not?

-- 
Happy hacking
Petter Reinholdtsen