[PATCH v3 0/4] Fix Win8 backlight issue

[Aaron Lu]

On Wed, Sep 25, 2013 at 10:29:37AM +0200, Jörg Otte wrote:
> Backlight can't be modified with this patch set -  neither with function
> keys nor
> with the gui. It is a step backward to v3.11-rc1

Thanks for the test.

Please check /sys/class/backlight, is there only one link file
intel_backlight? If so, please cd inside and try modify the brightness
file using echo with some values in the range of 0 - max_brightness,
does the backlight level change when you echo a new value? I guess it
doesn't, or you wouldn't notice problem. If indeed so, perhaps file a
bug at http://bugzilla.kernel.org, Drivers/Video(DRI-Intel)? I suppose
Jani and Daniel can help fix your problem.

Thanks,
Aaron

> 
> Video driver: i915
> FUJITSU LIFEBOOK AH532/FJNBB1C, BIOS Version 1.09 05/22/2012
> 
> acpi_backlight=video works.
> 
> Jörg
> 
> 
> 2013/9/24 Igor Gnatenko <i.gnatenko.brain at gmail.com>
> 
> > On Tue, 2013-09-24 at 17:47 +0800, Aaron Lu wrote:
> > > v3:
> > > 1 Add a new patch 4/4 to fix some problems in thinkpad-acpi module;
> > > 2 Remove unnecessary function acpi_video_unregister introduced in
> > >   patch 2/3 as pointed out by Jani Nikula.
> > >
> > > v2:
> > > 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.
> > >
> > > Aaron Lu (4):
> > >   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
> > >   thinkpad-acpi: fix handle locate for video and query of _BCL
> > >
> > >  drivers/acpi/internal.h              |   5 +-
> > >  drivers/acpi/video.c                 | 442
> > ++++++++++++++++++++---------------
> > >  drivers/acpi/video_detect.c          |  14 +-
> > >  drivers/platform/x86/thinkpad_acpi.c |  31 ++-
> > >  drivers/video/backlight/backlight.c  |  31 +++
> > >  include/acpi/video.h                 |   2 +
> > >  include/linux/backlight.h            |   4 +
> > >  7 files changed, 324 insertions(+), 205 deletions(-)
> > >
> >
> > Excellent! I've tested this patch-set on ThinkPad X230 and backlight
> > issue is exhausted.
> >
> > Thanks.
> >
> > --
> > Igor Gnatenko
> > Fedora release 20 (Heisenbug)
> > Linux 3.11.1-300.fc20.x86_64
> >
> >