[HP EliteBook Folio 9470m Notebook PC] Backlight does not work on intel driver after upgrade from 13.10 -> 14.04, acpi_backlight=vendor solves

Seems this is a kernel/firmware/acpi issue.

I just booted with acpi_backlight=vendor and that solves the issue. Happy to help debug the issue to help other users of this hardware avoid the problem.

This change was made by a bot.

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.15 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/v3.15-rc2-trusty/

Tested with 3.15-rc2, backlight control still did not work.

I'd like to perform a bisect to figure out what commit caused this regression. We need to identify the earliest kernel where the issue started happening as well as the latest kernel that did not have this issue.

Can you test the following kernels and report back? We are looking for the first kernel version that exhibits this bug:

v3.12 final: http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-trusty/
If v3.12 final does not exhibit the bug, we should move on to testing some of the v3.13 release candidates.

v3.13-rc3: http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.13-rc3-trusty/

If v3.13-rc3 does not exhibit the bug then test v3.13-rc6:
v3.13-rc6: http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.13-rc6-trusty/

If v3.13-rc3 does exhibit the bug then test v3.13-rc2:
v3.13-rc2: http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.13-rc2-trusty

You don't have to test every kernel, just up until the kernel that first has this bug.

Thanks in advance!

Trying 3.12 now. Note that I discovered a new symptom today: when a monitor is plugged into the DisplayPort, the brightness controls in "Brightness and Lock" work, but the keyboard controls still don't work.

Backlight controls work flawlessly with 3.12 final.

Actually.. this is quite embarrassing, I installed 3.12, but my system didn't show a grub menu and I actually booted 3.13.0-24-generic

Not sure how that happened, but it actually appears that the issue has gone away somehow. Could still be a race maybe?

Hmm, do you still have acpi_backlight=vendor? If not, I guess it would be good to test the 3.13.0-24-generic kernel for a while to ensure the bug doesn't come back.

Excerpts from Joseph Salisbury's message of 2014-04-23 18:46:43 UTC:
> Hmm, do you still have acpi_backlight=vendor? If not, I guess it would
> be good to test the 3.13.0-24-generic kernel for a while to ensure the
> bug doesn't come back.
>

I do not.

I wonder if it is also possible that I booted w/ EFI or something else
that caused this.

FYI, I have experienced this again. It seems to only happen on resume
from suspend.

Excerpts from Joseph Salisbury's message of 2014-05-13 18:34:24 UTC:
> ** Changed in: linux (Ubuntu)
> Status: Triaged => Incomplete
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1309584
>
> Title:
> [HP EliteBook Folio 9470m Notebook PC] Backlight does not work on
> intel driver after upgrade from 13.10 -> 14.04, acpi_backlight=vendor
> solves
>
> Status in “linux” package in Ubuntu:
> Incomplete
>
> Bug description:
> I am running on an HP EliteBook Folio 9470m which has an i915 video
> chipset.
>
> After upgrading to 14.04, the backlight and brightness controls do not
> work on the laptop screen.
>
> $ sudo intel_backlight
> current backlight value: 4%
>
> ProblemType: Bug
> DistroRelease: Ubuntu 14.04
> Package: xserver-xorg-video-intel 2:2.99.910-0ubuntu1
> ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
> Uname: Linux 3.13.0-24-generic x86_64
> .tmp.unity.support.test.0:
>
> ApportVersion: 2.14.1-0ubuntu3
> Architecture: amd64
> CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
> CompositorRunning: compiz
> CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
> CompositorUnredirectFSW: true
> CurrentDesktop: Unity
> Date: Fri Apr 18 08:02:05 2014
> DistUpgraded: 2014-04-18 01:03:05,027 DEBUG enabling apt cron job
> DistroCodename: trusty
> DistroVariant: ubuntu
> DkmsStatus: openvswitch, 2.0.1+git20140120: added
> ExtraDebuggingInterest: Yes, including running git bisection searches
> GraphicsCard:
> Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
> Subsystem: Hewlett-Packard Company Device [103c:18df]
> InstallationDate: Installed on 2013-01-14 (459 days ago)
> InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64+mac (20121017.3)
> MachineType: Hewlett-Packard HP EliteBook Folio 9470m
> ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-24-generic root=/dev/mapper/ubuntu-root ro quiet splash "acpi_osi=!Windows 2012" vt.handoff=7
> SourcePackage: xserver-xorg-video-intel
> UpgradeStatus: Upgraded to trusty on 2014-04-18 (0 days ago)
> dmi.bios.date: 09/24/2012
> dmi.bios.vendor: Hewlett-Packard
> dmi.bios.version: 68IBD Ver. F.30
> dmi.board.name: 18DF
> dmi.board.vendor: Hewlett-Packard
> dmi.board.version: KBC Version 62.13
> dmi.chassis.asset.tag: CNU2439PZT
> dmi.chassis.type: 10
> dmi.chassis.vendor: Hewlett-Packard
> dmi.modalias: dmi:bvnHewlett-Packard:bvr68IBDVer.F.30:bd09/24/2012:svnHewlett-Packard:pnHPEliteBookFolio9470m:pvrA1029D1103:rvnHewlett-Packard:rn18DF:rvrKBCVersion62.13:cvnHewlett-Packard:ct10:cvr:
> dmi.product.name: HP EliteBook Folio 9470m
> dmi.product.version: A1029D1103
> dmi.sys.vendor: Hewlett-Packard
> version.compiz: compiz 1:0.9.11+14.04.20140409-0ubuntu1
> version.ia32-libs: ia32-libs N/A
> version.libdrm2: libdrm2 2.4.52-1
> version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.0-4ubuntu5
> ...

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]