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Hans de Goede 378259c7d0 ACPI / video: Default lcd_only to true on Win8-ready and newer machines
[ Upstream commit 5928c28152 ]

We're seeing a lot of bogus backlight interfaces on newer machines without
a LCD such as desktops, servers and HDMI sticks. This causes userspace to
show a non-functional brightness slider in e.g. the GNOME3 system menu,
which is undesirable. And, in general, we should simply just not register
a non functional backlight interface.

Checking the LCD flag causes the bogus acpi_video backlight interfaces to
go away (on the machines this was tested on).

This change sets the lcd_only option by default on any machines which
are Win8-ready, to fix this.

This is not entirely without a risk of regressions, but video_detect.c
already prefers native-backlight interfaces over the acpi_video one
on Win8-ready machines, calling acpi_video_unregister_backlight() as soon
as a native interface shows up. This is done because the ACPI backlight
interface often is broken on Win8-ready machines, because win8 does not
seem to actually use it.

So in practice we already end up not registering the ACPI backlight
interface on (most) Win8-ready machines with a LCD panel, thus this
change does not change anything for (most) machines with a LCD panel
and on machines without a LCD panel we actually don't want to register
any backlight interfaces.

This has been tested on the following machines and fixes a bogus backlight
interface showing up there:
 - Desktop with an Asrock B150M Pro4S/D3 m.b. using i5-6500 builtin gfx
 - Intel Compute Stick STK1AW32SC
 - Meegopad T08 HDMI stick

Bogus backlight interfaces have also been reported on:
 - Desktop with Asus H87I-Plus m.b.
 - Desktop with ASRock B75M-ITX m.b.
 - Desktop with Gigabyte Z87-D3HP m.b.
 - Dell PowerEdge T20 desktop

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1097436
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133327
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133329
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1133646
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2018-04-12 12:32:13 +02:00
arch ARM: dts: ls1021a: add "fsl,ls1021a-esdhc" compatible string to esdhc node 2018-04-12 12:32:11 +02:00
block Fix slab name "biovec-(1<<(21-12))" 2018-04-08 14:26:33 +02:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: ahash - Fix early termination in hash walk 2018-04-08 14:26:31 +02:00
Documentation serial: 8250: Add Nuvoton NPCM UART 2018-04-08 14:26:30 +02:00
drivers
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs Btrfs: fix unexpected cow in run_delalloc_nocow 2018-04-08 14:26:32 +02:00
include serial: 8250: Add Nuvoton NPCM UART 2018-04-08 14:26:30 +02:00
init kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2018-02-22 15:42:23 +01:00
ipc ipc/shm.c: add split function to shm_vm_ops 2018-04-08 14:26:27 +02:00
kernel perf/hwbp: Simplify the perf-hwbp code, fix documentation 2018-04-08 14:26:27 +02:00
lib rhashtable: Fix rhlist duplicates insertion 2018-03-31 18:10:40 +02:00
mm percpu: add __GFP_NORETRY semantics to the percpu balancing path 2018-04-08 14:26:29 +02:00
net rds; Reset rs->rs_bound_addr in rds_add_bound() failure path 2018-04-12 12:32:12 +02:00
samples samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp1 2017-12-20 10:10:31 +01:00
scripts kbuild: fix linker feature test macros when cross compiling with Clang 2018-03-24 11:01:29 +01:00
security /dev/mem: Add bounce buffer for copy-out 2018-03-24 11:01:24 +01:00
sound ALSA: pcm: potential uninitialized return values 2018-04-08 14:26:27 +02:00
tools perf evsel: Enable ignore_missing_thread for pid option 2018-04-12 12:32:12 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: vgic: Don't populate multiple LRs with the same vintid 2018-03-21 12:06:43 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.33 2018-04-08 14:26:34 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.