Packard Bell EasyNote LV need i915.invert_brightness=1

[Daniel Vetter]

On Thu, Jun 27, 2013 at 3:03 PM, Petter Reinholdtsen <pere at hungry.com> wrote:
> [Daniel Vetter]
>> acpi_backlight=vendor should disable the acpi backlights (you can
>> check that in /sys/class/backlight), which would mean that userspace
>> should fall back to intel backlight driver. Can you please check
>> whether that one works even without the invert_brightness knob? I.e.
>> not just whether you'll end up with a black screen, but whether
>> adjusting the backlight also works correctly.
>
> Adjusting backlight using the laptop keys for this work in KDE when I
> boot with acpi_backlight=vendor and without invert_brightness=1.  I am
> not sure if the buttons work the right way, though (never seen which
> should increase or decrease the brighness), so it might be inverted.

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?

> Is it possible to tell acpi_backlight to invert the brighness setting?
> Would it affect i915 too?

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