[Dell Inspiron 3531] Brightness control does not work on 14.04.1

[Po-Hsu Lin]

CID: 201403-14892 Inspiron 3531

Brightness control does not work on this system
The brightness level indicator would change with hotkey events, but the brightness itself does not.

Debugging information:
ubuntu@201403-14892:~$ ls /sys/class/backlight
acpi_video0 intel_backlight

ubuntu@201403-14892:~$ grep -r . /proc/acpi
/proc/acpi/battery/BAT1/alarm:alarm: unsupported
/proc/acpi/battery/BAT1/state:present: yes
/proc/acpi/battery/BAT1/state:capacity state: ok
/proc/acpi/battery/BAT1/state:charging state: charged
/proc/acpi/battery/BAT1/state:present rate: 1 mA
/proc/acpi/battery/BAT1/state:remaining capacity: 2508 mAh
/proc/acpi/battery/BAT1/state:present voltage: 17028 mV
/proc/acpi/battery/BAT1/info:present: yes
/proc/acpi/battery/BAT1/info:design capacity: 2800 mAh
/proc/acpi/battery/BAT1/info:last full capacity: 2508 mAh
/proc/acpi/battery/BAT1/info:battery technology: rechargeable
/proc/acpi/battery/BAT1/info:design voltage: 14800 mV
/proc/acpi/battery/BAT1/info:design capacity warning: 250 mAh
/proc/acpi/battery/BAT1/info:design capacity low: 75 mAh
/proc/acpi/battery/BAT1/info:cycle count: 0
/proc/acpi/battery/BAT1/info:capacity granularity 1: 264 mAh
/proc/acpi/battery/BAT1/info:capacity granularity 2: 3780 mAh
/proc/acpi/battery/BAT1/info:model number: DELL T1G4M2CK
/proc/acpi/battery/BAT1/info:serial number: 0E4C
/proc/acpi/battery/BAT1/info:battery type: Li-Ion
/proc/acpi/battery/BAT1/info:OEM info: LGC
/proc/acpi/button/lid/LID0/state:state: open
/proc/acpi/ac_adapter/ACAD/state:state: on-line
/proc/acpi/wakeup:Device S-state Status Sysfs node
/proc/acpi/wakeup:LID0 S3 *enabled
/proc/acpi/wakeup:RP01 S4 *disabled pci:0000:00:1c.0
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP02 S4 *disabled pci:0000:00:1c.1
/proc/acpi/wakeup:PXSX S4 *disabled pci:0000:02:00.0
/proc/acpi/wakeup:RP03 S4 *disabled pci:0000:00:1c.2
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:RP04 S4 *disabled pci:0000:00:1c.3
/proc/acpi/wakeup:PXSX S4 *disabled
/proc/acpi/wakeup:EHC1 S0 *enabled pci:0000:00:1d.0
/proc/acpi/wakeup:PWRB S4 *enabled

ubuntu@201403-14892:~$ dmesg | grep 'ACPI: Video'
[ 17.318290] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)
ubuntu@201403-14892:~$

WORKAROUND:
Adding "acpi_backlight=vendor" to grub could make it work.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-39-generic 3.13.0-39.66
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1520 F.... pulseaudio
CRDA:
 country TW:
  (2402 - 2472 @ 40), (3, 27)
  (5270 - 5330 @ 40), (3, 17), DFS
  (5735 - 5815 @ 40), (3, 30)
CurrentDesktop: Unity
Date: Mon Nov 17 21:37:21 2014
HibernationDevice: RESUME=UUID=217ae5ce-6101-4b1d-8ed3-e5df8cacfafa
InstallationDate: Installed on 2014-11-17 (0 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
Lsusb:
 Bus 001 Device 005: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
 Bus 001 Device 004: ID 1a40:0101 Terminus Technology Inc. Hub
 Bus 001 Device 003: ID 0c45:64ad Microdia
 Bus 001 Device 002: ID 8087:07e6 Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Inspiron 3531
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-39-generic root=UUID=34aa7766-e502-48af-81d4-5a155b69c395 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-39-generic N/A
 linux-backports-modules-3.13.0-39-generic N/A
 linux-firmware 1.127.8
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/02/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A02_UpdateMCU
dmi.board.name: 00FTTX
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A02_UpdateMCU
dmi.modalias: dmi:bvnDellInc.:bvrA02_UpdateMCU:bd07/02/2014:svnDellInc.:pnInspiron3531:pvrA02_UpdateMCU:rvnDellInc.:rn00FTTX:rvrA00:cvnDellInc.:ct8:cvrA02_UpdateMCU:
dmi.product.name: Inspiron 3531
dmi.product.version: A02_UpdateMCU
dmi.sys.vendor: Dell Inc.

[Po-Hsu Lin (cypressyew)]

Note that this bug seems to be the only blocker to this system, 201403-14892 Inspiron 3531
It will be great to have it fixed in 3.13 kernel.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Po-Hsu Lin (cypressyew)]

Another issue found on this system, bug 1393651
Let's see whether this is a blocker or not.

[Po-Hsu Lin (cypressyew)]

Also affect 201404-14984 Dell Inspiron 3531

Bug 1393651 is a blocker.

[Anthony Wong (anthonywong)]

The OEM bug is LP #1304182, in which acpi_backlight=vendor is used to fix it. We need a proper fix in kernel to close this cert blocker.

[Joseph Patrick Copenhaver (joseph-copenhaver)]

I'd be interested in workaround steps once they become available :-)

[Anthony Wong (anthonywong)]

@Joseph
To workaround, append acpi_backlight=vendor on line GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub, then run 'sudo update-grub'.

[Anthony Wong (anthonywong)]

@PHLin
Can you give the kernel param video.use_native_backlight=1", or utopic 3.16 kernel a try?

[Po-Hsu Lin (cypressyew)]

Verified with kernel parameter video.use_native_backlight=1 and 3.16 kernel
Both of them could make the brightness control back to work.
Thanks