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2014-09-24ACPI / video: force vendor backlight on Lenovo Ideapad Z570Stepan Bujnak1-0/+8
Lenovo Ideapad 570 is a pre-win8 laptop where not using vendor backlight causes the backlight controls not to work. Signed-off-by: Stepan Bujnak <stepanbujnak@fastmail.fm> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-07-07ACPI / video: Add Dell Inspiron 5737 to the blacklistEdward Lin1-0/+8
With win8 capabiltiy, the ACPI backlight control is broken. The system also loses backlight setting when resuming from S3. Add this model to the the ACPI video detect blacklist to make backlight functionality work. Although backlight functionality works via video.use_native_backlight=1, this approach may be safer. Signed-off-by: Edward Lin <yidi.lin@canonical.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-03-19ACPI: Remove duplicate definitions of PREFIXHanjun Guo1-2/+0
We already have a macro for PREFIX of "ACPI: " in drivers/acpi/internal.h, so remove the duplicate ones in ACPI drivers when internal.h is included. Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-20ACPI / video: Add systems that should favour native backlight interfaceAaron Lu1-16/+0
Some system's ACPI video backlight control interface is broken and the native backlight control interface should be used by default. This patch sets the use_native_backlight parameter to true for those systems so that video backlight control interface will not be created. For detailed models that are added here, reference the following list. Note that the user specified kernel cmdline option will always have the highest priority, i.e. if use_native_backlight=0 is specified and the system is in the DMI table, the video module will not skip registering backlight interface for it. Thinkpad T430s: Reported-by: Theodore Tso <tytso@mit.edu> Reported-and-tested-by: Peter Weber <bugs@ttyhoney.com> References: https://bugzilla.kernel.org/show_bug.cgi?id=51231 Thinkpad X230: Reported-and-tested-by: Igor Gnatenko <i.gnatenko.brain@gmail.com> References: https://bugzilla.kernel.org/show_bug.cgi?id=51231 ThinkPad X1 Carbon: Reported-and-tested-by: Igor Gnatenko <i.gnatenko.brain@gmail.com> Lenovo Yoga 13: Reported-by: Lennart Poettering <lennart@poettering.net> Reported-and-tested-by: Kevin Smith <thirdwiggin@gmail.com> References: https://bugzilla.kernel.org/show_bug.cgi?id=63811 Dell Inspiron 7520: Reported-by: Rinat Ibragimov <ibragimovrinat@mail.ru> Acer Aspire 5733Z: Reported-by: <sov.info@mail.ru> References: https://bugzilla.kernel.org/show_bug.cgi?id=62941 Acer Aspire V5-431: Reported-by: Thomas Christensen <christensenthomas@gmail.com> References: https://bugzilla.kernel.org/show_bug.cgi?id=68751 HP ProBook 4340s: Reported-and-tested-by: Vladimir Sherenkov <a_12300@mail.ru> References: http://redmine.russianfedora.pro/issues/1258 HP EliteBook/ProBook 2013 models, ZBook and some others: Provided-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-02-05ACPI / video: Add HP EliteBook Revolve 810 to the blacklistMika Westerberg1-0/+8
On HP EliteBook Revolve 810 the ACPI backlight device doesn't work as expected. For example when resuming from system sleep, it seems to lose backlight settings. Forcing Intel driver fixes the problem so add this machine the ACPI video detect blacklist. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-12-20ACPI / video: Fix typo in video_detect.cMasanari Iida1-1/+1
Correct "**retyurn_value" to "**return_value". Signed-off-by: Masanari Iida <standby24x7@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-16ACPI / video: Add Lenovo IdeaPad Yoga 13 to acpi video detect blacklistLennart Poettering1-0/+8
On the Yoga 13 the backlight control doesn't work via ACPI. (And doesn't work either with the low-level platform driver ideapad_laptop; but works correctly via the intel video driver). This patch hence adds the Yoga 13 to the ACPI video detect blacklist, to make sure the broken ACPI backlight device is never exposed to userspace. Note that this appears unrelated to the Windows 8 backlight issues tracked here: https://bugzilla.kernel.org/show_bug.cgi?id=51231 https://bugzilla.kernel.org/show_bug.cgi?id=60682 The Yoga's ACPI backlight controls work neither with nor without acpi_osi="!Windows 2012" on the kernel command line. It appears that backlight control via the EC simply is not available at all, regardless whether done via ACPI or via the vendor driver. Signed-off-by: Lennart Poettering <lennart@poettering.net> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-16ACPI / video: Do not register backlight if win8 and native interface existsAaron Lu1-2/+2
According to Matthew Garrett, "Windows 8 leaves backlight control up to individual graphics drivers rather than making ACPI calls itself. There's plenty of evidence to suggest that the Intel driver for Windows [8] doesn't use the ACPI interface, including the fact that it's broken on a bunch of machines when the OS claims to support Windows 8. The simplest thing to do appears to be to disable the ACPI backlight interface on these systems". So for Win8 systems, if there is native backlight control interface registered by GPU driver, ACPI video does not need to register its own. Since there are systems that don't work well with this approach, a parameter for video module named use_native_backlight is introduced and has the value of false by default. For users who have a broken ACPI video backlight interface, video.use_native_backlight=1 is needed in kernel cmdline. Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-08-27Merge branch 'acpi-cleanup'Rafael J. Wysocki1-11/+8
* acpi-cleanup: (21 commits) ACPI / dock: fix error return code in dock_add() ACPI / dock: Drop unnecessary local variable from dock_add() ACPI / dock / PCI: Drop ACPI dock notifier chain ACPI / dock: Do not check CONFIG_ACPI_DOCK_MODULE ACPI / dock: Do not leak memory on falilures to add a dock station ACPI: Drop ACPI bus notifier call chain ACPI / dock: Rework the handling of notifications ACPI / dock: Simplify dock_init_hotplug() and dock_release_hotplug() ACPI / dock: Walk list in reverse order during removal of devices ACPI / dock: Rework and simplify find_dock_devices() ACPI / dock: Drop the hp_lock mutex from struct dock_station ACPI: simplify acpiphp driver with new helper functions ACPI: simplify dock driver with new helper functions ACPI: Export acpi_(bay)|(dock)_match() from scan.c ACPI: introduce two helper functions for _EJ0 and _LCK ACPI: introduce helper function acpi_execute_simple_method() ACPI: introduce helper function acpi_has_method() ACPI / dock: simplify dock_create_acpi_device() ACPI / dock: mark initialization functions with __init ACPI / dock: drop redundant spin lock in dock station object ...
2013-07-26Revert "ACPI / video / i915: No ACPI backlight if firmware expects Windows 8"Rafael J. Wysocki1-14/+1
We attempted to address a regression introduced by commit a57f7f9 (ACPICA: Add Windows8/Server2012 string for _OSI method.) after which ACPI video backlight support doesn't work on a number of systems, because the relevant AML methods in the ACPI tables in their BIOSes become useless after the BIOS has been told that the OS is compatible with Windows 8. That problem is tracked by the bug entry at: https://bugzilla.kernel.org/show_bug.cgi?id=51231 Commit 8c5bd7a (ACPI / video / i915: No ACPI backlight if firmware expects Windows 8) introduced for this purpose essentially prevented the ACPI backlight support from being used if the BIOS had been told that the OS was compatible with Windows 8 and the i915 driver was loaded, in which case the backlight would always be handled by i915. Unfortunately, however, that turned out to cause problems with backlight to appear on multiple systems with symptoms indicating that i915 was unable to control the backlight on those systems as expected. For this reason, revert commit 8c5bd7a, but leave the function acpi_video_backlight_quirks() introduced by it, because another commit on top of it uses that function. References: https://lkml.org/lkml/2013/7/21/119 References: https://lkml.org/lkml/2013/7/22/261 References: https://lkml.org/lkml/2013/7/23/429 References: https://lkml.org/lkml/2013/7/23/459 References: https://lkml.org/lkml/2013/7/23/81 References: https://lkml.org/lkml/2013/7/24/27 Reported-and-tested-by: James Hogan <james@albanarts.com> Reported-and-tested-by: Kamal Mostafa <kamal@canonical.com> Reported-and-tested-by: Jörg Otte <jrg.otte@gmail.com> Reported-and-tested-by: Steven Newbury <steve@snewbury.org.uk> Reported-by: Martin Steigerwald <Martin@lichtvoll.de> Reported-by: Kalle Valo <kvalo@adurom.com> Tested-by: Joerg Platte <jplatte@naasa.net> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-07-18ACPI / video / i915: No ACPI backlight if firmware expects Windows 8Rafael J. Wysocki1-0/+21
According to Matthew Garrett, "Windows 8 leaves backlight control up to individual graphics drivers rather than making ACPI calls itself. There's plenty of evidence to suggest that the Intel driver for Windows [8] doesn't use the ACPI interface, including the fact that it's broken on a bunch of machines when the OS claims to support Windows 8. The simplest thing to do appears to be to disable the ACPI backlight interface on these systems". There's a problem with that approach, however, because simply avoiding to register the ACPI backlight interface if the firmware calls _OSI for Windows 8 may not work in the following situations: (1) The ACPI backlight interface actually works on the given system and the i915 driver is not loaded (e.g. another graphics driver is used). (2) The ACPI backlight interface doesn't work on the given system, but there is a vendor platform driver that will register its own, equally broken, backlight interface if not prevented from doing so by the ACPI subsystem. Therefore we need to allow the ACPI backlight interface to be registered until the i915 driver is loaded which then will unregister it if the firmware has called _OSI for Windows 8 (or will register the ACPI video driver without backlight support if not already present). For this reason, introduce an alternative function for registering ACPI video, acpi_video_register_with_quirks(), that will check whether or not the ACPI video driver has already been registered and whether or not the backlight Windows 8 quirk has to be applied. If the quirk has to be applied, it will block the ACPI backlight support and either unregister the backlight interface if the ACPI video driver has already been registered, or register the ACPI video driver without the backlight interface otherwise. Make the i915 driver use acpi_video_register_with_quirks() instead of acpi_video_register() in i915_driver_load(). This change is based on earlier patches from Matthew Garrett, Chun-Yi Lee and Seth Forshee and includes a fix from Aaron Lu's. References: https://bugzilla.kernel.org/show_bug.cgi?id=51231 Tested-by: Aaron Lu <aaron.lu@intel.com> Tested-by: Igor Gnatenko <i.gnatenko.brain@gmail.com> Tested-by: Yves-Alexis Perez <corsac@debian.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Aaron Lu <aaron.lu@intel.com> Acked-by: Matthew Garrett <matthew.garrett@nebula.com>
2013-07-15ACPI: introduce helper function acpi_has_method()Jiang Liu1-11/+8
Introduce helper function acpi_has_method() and use it in a number of places to simplify code. [rjw: Changelog] Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-23ACPI / video: Add "Asus UL30A" to ACPI video detect blacklistBastian Triller1-0/+8
Like on UL30VT, the ACPI video driver can't control backlight correctly on Asus UL30A. Vendor driver (asus-laptop) can work. This patch is to add "Asus UL30A" to ACPI video detect blacklist in order to use asus-laptop for video control on the "Asus UL30A" rather than ACPI video driver. Signed-off-by: Bastian Triller <bastian.triller@gmail.com> Cc: All <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-24ACPI: Remove acpi_device dependency in acpi_device_set_id()Toshi Kani1-14/+11
This patch updates the internal operations of acpi_device_set_id() to setup acpi_device_pnp without using acpi_device. There is no functional change to acpi_device_set_id() in this patch. acpi_pnp_type is added to acpi_device_pnp, so that PNPID type is self-contained within acpi_device_pnp. acpi_add_id(), acpi_bay_match(), acpi_dock_match(), acpi_ibm_smbus_match() and acpi_is_video_device() are changed to take acpi_handle as an argument, instead of acpi_device. Signed-off-by: Toshi Kani <toshi.kani@hp.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-30ACPI / video: Add "Asus UL30VT" to ACPI video detect blacklistLan Tianyu1-0/+8
The ACPI video driver can't control backlight correctly on Asus UL30VT. Vendor driver (asus-laptop) can work. This patch is to add "Asus UL30VT" to ACPI video detect blacklist in order to use asus-laptop for video control on the "Asus UL30VT" rather than ACPI video driver. References: https://bugzilla.kernel.org/show_bug.cgi?id=32592 Reported-by: Alex Williamson <alex.williamson@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-07-28acpi/video_detect: blacklist samsung x360Corentin Chary1-0/+29
On Samsung X360, the BIOS will set a flag (VDRV) if the generic ACPI backlight device is used. This flag will definitively break the backlight interface (even the vendor interface) untill next reboot. It's why we should prevent video.ko from being used here and we can't rely on a later call to acpi_video_unregister(). Signed-off-by: Corentin Chary <corentin.chary@gmail.com> Signed-off-by: Matthew Garrett <mjg@redhat.com>
2012-07-28acpi: add a way to promote/demote vendor backlight driversCorentin Chary1-2/+29
Instead of adding a big blacklist in video_detect.c to set ACPI_VIDEO_BACKLIGHT_DMI_VENDOR correctly, let external modules promote or demote themselves when they know the generic video module won't work. Currently drivers where using acpi_video_unregister() directly but: - That didn't respect any acpi_backlight=[video|vendor] parameter provided by the user. - Any later call to acpi_video_register() would still re-load the generic video module (and some gpu drivers are doing that). This patch fix those two issues. Signed-off-by: Corentin Chary <corentin.chary@gmail.com> Signed-off-by: Matthew Garrett <mjg@redhat.com>
2012-03-20platform/x86: drop deprecated asus_acpi driverCorentin Chary1-1/+1
asus_acpi only support old models, it has been deprecated since 2009 in favor of asus-laptop, it's not built by any (sane) distro, so it is time to say good bye. Thanks to Julien Lerouge and Karol Kozimor for the work they have done on it, I would never have wrote asus-laptop and other asus related drivers without asus_acpi. Signed-off-by: Corentin Chary <corentin.chary@gmail.com> Signed-off-by: Matthew Garrett <mjg@redhat.com>
2011-10-31acpi: add export.h to files using THIS_MODULE/EXPORT_SYMBOLPaul Gortmaker1-0/+1
These files were relying on module.h to come in via the path in an include/acpi header file, but we don't want to have instances of module.h being included from include/* files if it can be avoided. Have the files include export.h instead. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-02-12ACPI / Video: Probe for output switch method when searching video devices.Michael Karcher1-0/+5
This patch reverts one hunk of 677bd810eedce61edf15452491781ff046b92edc "ACPI video: remove output switching control", namely the removal of probing for _DOS/_DOD when searching for video devices. This is needed on some Fujitsu Laptops (at least S7110, P8010) for the ACPI backlight interface to work, as an these machines, neither ROM nor posting methods are available, and after removal of output switching, none of the caps triggers, which prevents the backlight search from being entered. Tested on a Fujitsu Lifebook S7110 and Fujitsu Lifebook P8010. This probably fixes https://bugzilla.kernel.org/show_bug.cgi?id=27312 for the people who have no entry in /sys/class/backlight. This is the complete list of public (starting with "_") methods implemented on the S7110, BIOS rev 1.34: \_SB_.PCI0.GFX0._ADR \_SB_.PCI0.GFX0._DOS \_SB_.PCI0.GFX0._DOD \_SB_.PCI0.GFX0.CRT._ADR \_SB_.PCI0.GFX0.CRT._DCS \_SB_.PCI0.GFX0.CRT._DGS \_SB_.PCI0.GFX0.CRT._DSS \_SB_.PCI0.GFX0.LCD._ADR \_SB_.PCI0.GFX0.LCD._BCL \_SB_.PCI0.GFX0.LCD._BCM \_SB_.PCI0.GFX0.LCD._BQC \_SB_.PCI0.GFX0.LCD._DCS \_SB_.PCI0.GFX0.LCD._DGS \_SB_.PCI0.GFX0.LCD._DSS \_SB_.PCI0.GFX0.LCD._PS0 \_SB_.PCI0.GFX0.LCD._PS3 \_SB_.PCI0.GFX0.TV._ADR \_SB_.PCI0.GFX0.TV._DCS \_SB_.PCI0.GFX0.TV._DGS \_SB_.PCI0.GFX0.TV._DSS \_SB_.PCI0.GFX0.DVI._ADR \_SB_.PCI0.GFX0.DVI._DCS \_SB_.PCI0.GFX0.DVI._DGS \_SB_.PCI0.GFX0.DVI._DSS Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de> Acked-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2010-12-14ACPI video: remove output switching controlZhang Rui1-53/+4
Remove the ACPI video output switching control as it never works. With the patch applied, ACPI video driver still catches the video output notification, but it does nothing but raises the notification to userspace. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2010-09-28ACPI video: fix a poor warning messageZhang Rui1-2/+2
Fix a vague warning message. https://bugzilla.kernel.org/show_bug.cgi?id=16599 Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2010-05-20ACPI: video: fix acpi_backlight=videoKamal Mostafa1-1/+1
Make "acpi_backlight=video" param enable ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO as intended, instead of incorrectly enabling video output switching. BugLink: http://bugs.launchpad.net/bugs/573120 Signed-off-by: Kamal Mostafa <kamal@canonical.com> Acked-by: Zhang Rui <rui.zhang@intel.com> Cc: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: <stable@kernel.org> Acked-by: Thomas Renninger <trenn@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Len Brown <len.brown@intel.com>
2009-12-09Merge branch 'acpica' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6Linus Torvalds1-3/+3
* 'acpica' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: ACPICA: Update version to 20091112. ACPICA: Add additional module-level code support ACPICA: Deploy new create integer interface where appropriate ACPICA: New internal utility function to create Integer objects ACPICA: Add repair for predefined methods that must return sorted lists ACPICA: Fix possible fault if return Package objects contain NULL elements ACPICA: Add post-order callback to acpi_walk_namespace ACPICA: Change package length error message to an info message ACPICA: Reduce severity of predefined repair messages, Warning to Info ACPICA: Update version to 20091013 ACPICA: Fix possible memory leak for Scope ASL operator ACPICA: Remove possibility of executing _REG methods twice ACPICA: Add repair for bad _MAT buffers ACPICA: Add repair for bad _BIF/_BIX packages
2009-12-04tree-wide: fix some typos and punctuation in commentsThadeu Lima de Souza Cascardo1-5/+5
fix some typos and punctuation in comments Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-11-24ACPICA: Add post-order callback to acpi_walk_namespaceLin Ming1-3/+3
The existing interface only has a pre-order callback. This change adds an additional parameter for a post-order callback which will be more useful for bus scans. ACPICA BZ 779. Also update the external calls to acpi_walk_namespace. http://www.acpica.org/bugzilla/show_bug.cgi?id=779 Signed-off-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-10-13ACPI: video: Loosen strictness of video bus detection codeStefan Bader1-1/+1
BugLink: http://bugs.launchpad.net/bugs/333386 Currently a video bus device must (beside other criteria) define _DOD and _DOS methods to be considered a video device. Some broken BIOSes prevented working backlight control by only defining both for one (non-existing bus) and only _DOD for the rest. With this patch in place the other bus definitions were considered too and backlight control started to work again. Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Acked-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-08-28ACPI: Move definition of PREFIX from acpi_bus.h to internal..hLen Brown1-0/+2
Linux/ACPI core files using internal.h all PREFIX "ACPI: ", however, not all ACPI drivers use/want it -- and they should not have to #undef PREFIX to define their own. Add GPL commment to internal.h while we are there. This does not change any actual console output, asside from a whitespace fix. Signed-off-by: Len Brown <len.brown@intel.com>
2009-06-17ACPI: video: convert to acpi_get_pci_devAlexander Chiang1-4/+5
Now that acpi_get_pci_dev is available, let's use it instead of acpi_get_physical_pci_device() Cc: Thomas Renninger <trenn@suse.de> Signed-off-by: Alex Chiang <achiang@hp.com> Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Len Brown <len.brown@intel.com>
2009-03-27ACPI video: add a warning message if _BQC is not foundZhang Rui1-0/+3
ACPI backlight control w/o _BQC support is kinda firmware bug. Add a warning if _BQC is not implemented. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
2008-12-30ACPI: ec.c, pci_link.c, video_detec.c: staticRoel Kluin1-2/+2
Sparse asked whether these could be static. Signed-off-by: Roel Kluin <roel.kluin@gmail.com> Signed-off-by: Len Brown <len.brown@intel.com>
2008-11-11Merge branch 'video' into releaseLen Brown1-0/+267
Conflicts: Documentation/kernel-parameters.txt Signed-off-by: Len Brown <len.brown@intel.com>
2008-11-07ACPI video: if no ACPI backlight support, use vendor driversThomas Renninger1-0/+268
If an ACPI graphics device supports backlight brightness functions (cmp. with latest ACPI spec Appendix B), let the ACPI video driver control backlight and switch backlight control off in vendor specific ACPI drivers (asus_acpi, thinkpad_acpi, eeepc, fujitsu_laptop, msi_laptop, sony_laptop, acer-wmi). Currently it is possible to load above drivers and let both poke on the brightness HW registers, the video and vendor specific ACPI drivers -> bad. This patch provides the basic support to check for BIOS capabilities before driver loading time. Driver specific modifications are in separate follow up patches. "acpi_backlight=vendor" Prever vendor driver over ACPI driver for backlight. "acpi_backlight=video" (default) Prever ACPI driver over vendor driver for backlight. Signed-off-by: Thomas Renninger <trenn@suse.de> Acked-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Len Brown <len.brown@intel.com>