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(-)