[Lenovo G780] Backlight switched off at login screen

[Danato]

Whenever I used to boot on ubuntu, my login screen was too dim, I wouldn't know my computer was switched on until I increased the brightness with my keyboard.

The problem is fixed going from http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12.1-trusty/ to http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12.2-trusty/ , specifically commit 2c62333a408f5badd2d2ffd7177f95deeccc5ca4 .

WORKAROUND: #!/bin/sh
cap_bright() {
   [ ! -d "$1" ] && return
    MAX=$(cat "$1/max_brightness")
    echo $MAX > "$1/brightness"
}
cap_bright "/sys/class/backlight/acpi_video1"
cap_bright "/sys/class/backlight/intel_backlight"

---
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: danato 1777 F.... pulseaudio
CRDA:
 country MO:
  (2402 - 2482 @ 40), (N/A, 20)
  (5170 - 5250 @ 40), (3, 23)
  (5250 - 5330 @ 40), (3, 23), DFS
  (5735 - 5835 @ 40), (3, 30)
DistroRelease: Ubuntu 13.10
InstallationDate: Installed on 2013-11-05 (5 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MachineType: LENOVO 20138
MarkForUpload: True
Package: linux (not installed)
ProcFB:
 0 nouveaufb
 1 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-13-generic root=UUID=be58180f-8d25-4719-a049-001ce96e4bb2 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
RelatedPackageVersions:
 linux-restricted-modules-3.11.0-13-generic N/A
 linux-backports-modules-3.11.0-13-generic N/A
 linux-firmware 1.116
StagingDrivers: rts5139
Tags: saucy staging
Uname: Linux 3.11.0-13-generic x86_64
UpgradeStatus: Upgraded to saucy on 2013-11-06 (5 days ago)
UserGroups: adm cdrom dip lpadmin netdev plugdev sambashare sudo
dmi.bios.date: 12/19/2012
dmi.bios.vendor: LENOVO
dmi.bios.version: 5ECN95WW(V9.00)
dmi.board.asset.tag: No Asset Tag
dmi.board.name: INVALID
dmi.board.vendor: LENOVO
dmi.board.version: 31900003WIN8 STD MLT
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo G780
dmi.modalias: dmi:bvnLENOVO:bvr5ECN95WW(V9.00):bd12/19/2012:svnLENOVO:pn20138:pvrLenovoG780:rvnLENOVO:rnINVALID:rvr31900003WIN8STDMLT:cvnLENOVO:ct10:cvrLenovoG780:
dmi.product.name: 20138
dmi.product.version: Lenovo G780
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1250051

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Danato (david-renato)]

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[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.12 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-trusty/

[Danato (david-renato)]

Thanks for the bios update heads up Christopher
I booted into windows and updated my bios, but there was no change as far as I could see,
and the same problem specified here persisted

sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

5ECN96WW(V9.01)
03/14/2013

[Danato (david-renato)]

Christopher, that kernel solved the problem. The backlight was working fine on a boot up.
But I'll wait for a stable release before I move to a new kernel.
Thanks for you advices

[Danato (david-renato)]

lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu Trusty Tahr (development branch)
Release: 14.04
Codename: trusty

Yes, I still have the same issue with this release

[Danato (david-renato)]

uname -a

Linux danato-Lenovo-G780 3.13.0-031300rc1-generic #201311221535 SMP Fri Nov 22 20:36:51 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

it also fixes the issue, I booted up with the maximum brightness

[Danato (david-renato)]

uname -a

Linux danato-Lenovo-G780 3.12.2-031202-generic #201311291538 SMP Fri Nov 29 20:39:07 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Boot up backlight working here too

[Danato (david-renato)]

I already knew that was coming so I started in advance

uname -a

Linux danato-Lenovo-G780 3.12.1-031201-generic #201311201654 SMP Wed Nov 20 21:54:49 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

The backlight didnt work on boot up here

[penalvch (penalvch)]

git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git && cd linux && git checkout 9efa5e50598c5568b0678bb411b239a0b6e9a328 && cp /boot/config-`uname -r` .config && yes '' | make oldconfig && make clean && make -j `getconf _NPROCESSORS_ONLN` deb-pkg LOCALVERSION=-custom && cd .. && sudo dpkg -i *.deb

[Danato (david-renato)]

uname -a
Linux danato-Lenovo-G780 3.12.0-rc4-custom #1 SMP Mon Dec 2 04:30:15 CST 2013 x86_64 x86_64 x86_64 GNU/Linux

The backlight ddnt work on that custom either, as you predicted

[penalvch (penalvch)]

Danato, ok now delete the .deb files made earlier and execute the following, which should work if it's the fix commit:
cd linux && git checkout 2c62333a408f5badd2d2ffd7177f95deeccc5ca4 && cp /boot/config-`uname -r` .config && yes '' | make oldconfig && make clean && make -j `getconf _NPROCESSORS_ONLN` deb-pkg LOCALVERSION=-custom && cd .. && sudo dpkg -i *.deb

[Danato (david-renato)]

uname -a
Linux danato-Lenovo-G780 3.12.0-rc4-custom #2 SMP Mon Dec 2 09:39:52 CST 2013 x86_64 x86_64 x86_64 GNU/Linux

Yup, this one works

[penalvch (penalvch)]

Danato, I'm going to marked this Triaged given we have identified the upstream fix commit, the commit is in mainline stable, and would be backported to Trusty.

[Danato (david-renato)]

I hope this report wasnt completely in vain, but I reported before it was fixed, so I wouldn't know anyways.
Thanks for your time Christopher, at least I learnt a few things doing this