https://bugzilla.kernel.org/show_bug.cgi?id=84221
Bug ID: 84221
Summary: Failure to recognize ATI backlight when off A/C
power/using battery power
Product: ACPI
Version: 2.5
Kernel Version: 3.16
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Power-Video
Assignee: [email protected]
Reporter: [email protected]
Regression: No
In versions prior to 3.16.0, ACPI was detected properly for intel_backlight and
acpi_video0/acpi_video1.
However, afterwards only intel_backlight is shown via sysfs.
This leads to full brightness (and unable to be altered) when this laptop is
plugged into A/C power, and when on battery power a completely disabled
backlight (leading to a VERY dim display) and backlight levels unable to be
altered.
lspci output:
[bts@workhorse ~]$ lspci | egrep -i 'vga|display'
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor
Graphics Controller (rev 09)
01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon
HD 8670A/8670M/8750M] (rev ff)
I've taken the liberty of bisecting, and have discovered the troublesome
behavior started with commit 751109aad5834375ca9ed0dcfcd85a00cbf872b:
751109aad5834375ca9ed0dcfcd85a00cbf872b5 is the first bad commit
commit 751109aad5834375ca9ed0dcfcd85a00cbf872b5
Author: Rafael J. Wysocki <[email protected]>
Date: Thu Jun 5 22:47:35 2014 +0200
ACPI / video: Change the default for video.use_native_backlight to 1
Now that we're hoping to have resolved all of the problems with
video.use_native_backlight=1, make that the default at last.
Link: http://marc.info/?l=linux-acpi&m=139716088401106&w=2
Signed-off-by: Rafael J. Wysocki <[email protected]>
:040000 040000 d8f9ae057c052cd94f1adcfc0b298db2c728a315
933b38080034b141fc0c31f54f38f5b232f69c17 M drivers
Bisect log:
[bts@workhorse linux-git]$ git bisect log
git bisect start
# bad: [19583ca584d6f574384e17fe7613dfaeadcdc4a6] Linux 3.16
git bisect bad 19583ca584d6f574384e17fe7613dfaeadcdc4a6
# good: [fad01e866afdbe01a1f3ec06a39c3a8b9e197014] Linux 3.15-rc8
git bisect good fad01e866afdbe01a1f3ec06a39c3a8b9e197014
# good: [7b215de3d0abbc4f6daf2efd19e8809af0564490] Merge branch 'i2c/for-next'
of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux into next
git bisect good 7b215de3d0abbc4f6daf2efd19e8809af0564490
# bad: [0430e49b6e7c6b5e076be8fefdee089958c9adad] ima: introduce
ima_kernel_read()
git bisect bad 0430e49b6e7c6b5e076be8fefdee089958c9adad
# good: [2937f5efa5754754daf46de745f67350f7f06ec2] Merge branch 'for_linus' of
git://cavan.codon.org.uk/platform-drivers-x86
git bisect good 2937f5efa5754754daf46de745f67350f7f06ec2
# good: [bc1dfff04a5d4064ba0db1fab13f84ab4f333d2b] Merge branch
'drm-nouveau-next' of git://anongit.freedesktop.org/git/nouveau/linux-2.6 into
drm-next
git bisect good bc1dfff04a5d4064ba0db1fab13f84ab4f333d2b
# good: [412dd3a6daf0cadce1b2d6a34fa3713f40255579] Merge tag
'xfs-for-linus-3.16-rc1' of git://oss.sgi.com/xfs/xfs
git bisect good 412dd3a6daf0cadce1b2d6a34fa3713f40255579
# good: [c31c24b8251fd44962a9b0bf82c770653bf07f6e] Merge branch 'next' of
git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux
git bisect good c31c24b8251fd44962a9b0bf82c770653bf07f6e
# good: [16b9057804c02e2d351e9c8f606e909b43cbd9e7] Merge branch 'for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
git bisect good 16b9057804c02e2d351e9c8f606e909b43cbd9e7
# bad: [19c1940feab777bb037c665a09f495d08a6c4e6c] Merge tag
'pm+acpi-3.16-rc1-2' of
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
git bisect bad 19c1940feab777bb037c665a09f495d08a6c4e6c
# good: [af76004cf8b4f368583bda22d7e348e40a338b91] Merge tag
'backlight-for-linus-3.16' of
git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight
git bisect good af76004cf8b4f368583bda22d7e348e40a338b91
# bad: [589e18a973bd6bb8abd2c6d4d8a1dcf5ae1dff61] Merge branch 'pm-cpufreq'
git bisect bad 589e18a973bd6bb8abd2c6d4d8a1dcf5ae1dff61
# good: [830bcac4e483d347087ed51eed564d1467e1e363] cpufreq: intel_pstate:
Remove duplicate CPU ID check
git bisect good 830bcac4e483d347087ed51eed564d1467e1e363
# good: [9d674f2107b7dc801db9780f5f6b645f4905372f] Merge branch 'acpi-hotplug'
git bisect good 9d674f2107b7dc801db9780f5f6b645f4905372f
# bad: [de815a6d00da0f8a59e8aebf8efe12e289552a8f] Merge branches 'acpi-general'
and 'acpi-video'
git bisect bad de815a6d00da0f8a59e8aebf8efe12e289552a8f
# good: [a4714a898e85205e1118ec923cde43d88eb105f6] ACPI: Fix bug when ACPI
reset register is implemented in system memory
git bisect good a4714a898e85205e1118ec923cde43d88eb105f6
# bad: [751109aad5834375ca9ed0dcfcd85a00cbf872b5] ACPI / video: Change the
default for video.use_native_backlight to 1
git bisect bad 751109aad5834375ca9ed0dcfcd85a00cbf872b5
# first bad commit: [751109aad5834375ca9ed0dcfcd85a00cbf872b5] ACPI / video:
Change the default for video.use_native_backlight to 1
Please let me know if there is any further information I can provide.
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