[PATCH v2 0/3] Fix Win8 backlight issue

[Aaron Lu <aaron.lu@intel.com>]

v1 has the subject of "Rework ACPI video driver" and is posted here:
http://lkml.org/lkml/2013/9/9/74
Since the objective is really to fix Win8 backlight issues, I changed
the subject in this version, sorry about that.

This patchset has three patches, the first introduced a new API named
backlight_device_registered in backlight layer that can be used for
backlight interface provider module to check if a specific type backlight
interface has been registered, see changelog for patch 1/3 for details.
Then patch 2/3 does the cleanup to sepeate the backlight control and
event delivery functionality in the ACPI video module and patch 3/3
solves some Win8 backlight control problems by avoiding register ACPI
video's backlight interface if:
1 Kernel cmdline option acpi_backlight=video is not given;
2 This is a Win8 system;
3 Native backlight control interface exists.

Technically, patch 2/3 is not required to fix the issue here. So if you
think it is not necessary, I can remove it from the series.

Apply on top of v3.12-rc1.

Aaron Lu (3):
  backlight: introduce backlight_device_registered
  ACPI / video: seperate backlight control and event interface
  ACPI / video: Do not register backlight if win8 and native interface
    exists

 drivers/acpi/internal.h             |   5 +-
 drivers/acpi/video.c                | 442 ++++++++++++++++++++----------------
 drivers/acpi/video_detect.c         |  14 +-
 drivers/video/backlight/backlight.c |  31 +++
 include/acpi/video.h                |   2 +
 include/linux/backlight.h           |   4 +
 6 files changed, 300 insertions(+), 198 deletions(-)

-- 
1.8.4.12.g2ea3df6