Public bug reported:
I can not modify the screen brightness in Ubuntu 17.10. Controls aside,
the classes in `proc` are either not available or non-functional
depending on what arguments I provide in GRUB_CMDLINE_LINUX_DEFAULT.
On a parallel installation (Ubuntu 16.04.3), brightness control works
flawlessly.
System Information
------------------
$ lsb_release -rd
Description: Ubuntu 17.10
Release: 17.10
$ lspci
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor
Host Bridge/DRAM Registers (rev 05)
00:01.0 PCI bridge: Intel Corporation Skylake PCIe Controller (x16) (rev 05)
00:08.0 System peripheral: Intel Corporation Skylake Gaussian Mixture Model
00:14.0 USB controller: Intel Corporation Sunrise Point-H USB 3.0 xHCI
Controller (rev 31)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-H Thermal
subsystem (rev 31)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-H Serial
IO I2C Controller #0 (rev 31)
00:16.0 Communication controller: Intel Corporation Sunrise Point-H CSME HECI
#1 (rev 31)
00:17.0 SATA controller: Intel Corporation Sunrise Point-H SATA controller
[AHCI mode] (rev 31)
00:1b.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Root Port #17 (rev f1)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #1
(rev f1)
00:1c.2 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #3
(rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #5
(rev f1)
00:1d.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #9
(rev f1)
00:1d.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #13
(rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-H LPC Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-H PMC (rev 31)
00:1f.3 Audio device: Intel Corporation Device a171 (rev 31)
00:1f.4 SMBus: Intel Corporation Sunrise Point-H SMBus (rev 31)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (5) I219-V
(rev 31)
01:00.0 VGA compatible controller: NVIDIA Corporation GM107GLM [Quadro M1200
Mobile] (rev a2)
01:00.1 Audio device: NVIDIA Corporation Device 0fbc (rev a1)
02:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD
Controller SM961/PM961
04:00.0 Network controller: Intel Corporation Wireless 8265 / 8275 (rev 78)
3e:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD
Controller SM961/PM961
# with GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi=Linux
thinkpad-acpi.brightness_enable=1":
$ grep . -R /sys/class/backlight/thinkpad_screen/*
/sys/class/backlight/thinkpad_screen/actual_brightness:0
/sys/class/backlight/thinkpad_screen/bl_power:0
/sys/class/backlight/thinkpad_screen/brightness:11
/sys/class/backlight/thinkpad_screen/max_brightness:15
/sys/class/backlight/thinkpad_screen/power/runtime_active_kids:0
/sys/class/backlight/thinkpad_screen/power/runtime_suspended_time:0
grep: /sys/class/backlight/thinkpad_screen/power/autosuspend_delay_ms:
Input/output error
/sys/class/backlight/thinkpad_screen/power/runtime_enabled:disabled
/sys/class/backlight/thinkpad_screen/power/runtime_active_time:0
/sys/class/backlight/thinkpad_screen/power/control:auto
/sys/class/backlight/thinkpad_screen/power/async:disabled
/sys/class/backlight/thinkpad_screen/power/runtime_usage:0
/sys/class/backlight/thinkpad_screen/power/runtime_status:unsupported
grep: warning:
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/subsystem:
recursive directory loop
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_active_kids:0
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_suspended_time:0
grep:
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/autosuspend_delay_ms:
Input/output error
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_enabled:disabled
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_active_time:0
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/control:auto
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/async:disabled
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_usage:0
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/power/runtime_status:unsupported
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/max_brightness:15
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/type:platform
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/brightness:11
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/bl_power:0
/sys/class/backlight/thinkpad_screen/subsystem/thinkpad_screen/actual_brightness:0
/sys/class/backlight/thinkpad_screen/type:platform
3f:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI
Express Card Reader (rev 01)
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: acpi brightness lenovo p51 thinkpad
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https://bugs.launchpad.net/bugs/1747273
Title:
Can not control brightness on Thinkpad P51
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