Vendor backlight on Lenovo Z580 having random hotkeys issues

[Neale Upstone]

I've taken a bold guess in the title of this bug.

While investigating why on 14.04 LTS, I have working backlight on the latest 3.13 kernel, but not on the 3.16, I tried acpi_backlight=vendor.

With default boot parameters, I just get /sys/class/backlight/intel_backlight/, and the backlight works correctly on 3.13, but does not change the brightness on 3.16 (the OSD does show that the hotkeys are trying to change the brightness).

With acpi_backlight=vendor, I get both intel and /lenovo/.

The key point for this bug report is what happens with the lenovo one:

The hotkeys work and make the backlight change, but not consistently. Repeatedly using the hotkey to increase the brightness causes the level to increase, but then occasionally reset to zero (including resetting as shown in the OSD - i.e. the OSD is always showing the level that the backlight actually is).

Occasionally the OSD shows the "enable touchpad" icon when pressing the increase brightness hotkey repeatedly. The same action also causes the wifi to enable/disable randomly.

If I press the hotkey with pauses in between, things behave normally.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-67-generic 3.13.0-67.110
ProcVersionSignature: Ubuntu 3.13.0-67.110-generic 3.13.11-ckt27
Uname: Linux 3.13.0-67-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.18
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: neale 3106 F.... pulseaudio
CurrentDesktop: Unity
Date: Sun Nov 15 11:16:55 2015
HibernationDevice: RESUME=UUID=1fd50851-1727-4432-a99c-d0be8aafc983
InstallationDate: Installed on 2013-10-23 (752 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: LENOVO IdeaPad Z580
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-67-generic root=UUID=d66417de-a540-485b-b469-aabd51a8844b ro quiet splash acpi_backlight=vendor
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-67-generic N/A
 linux-backports-modules-3.13.0-67-generic N/A
 linux-firmware 1.127.18
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: Upgraded to trusty on 2014-03-17 (607 days ago)
dmi.bios.date: 12/25/2012
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: 5FCN95WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: Lenovo
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 Z580
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr5FCN95WW:bd12/25/2012:svnLENOVO:pnIdeaPadZ580:pvrLenovoZ580:rvnLENOVO:rnLenovo:rvr31900003WIN8STDMLT:cvnLENOVO:ct10:cvrLenovoZ580:
dmi.product.name: IdeaPad Z580
dmi.product.version: Lenovo Z580
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This change was made by a bot.

[Neale Upstone (nealeu)]

BTW: The "bold guess in the title", won't make sense now, as the title was originally saying that I thought a register was being written incorrectly, until I realised that the backlight does work correctly and it seems to be hotkeys related.

If the implementation is idea_laptop.c then I'm taking a guess that this will also be a problem with more recent kernels. My first task, I guess is to boot 15.10 from a stick and see what I get with vendor.

[penalvch (penalvch)]

Neale Upstone, thank you for reporting this and helping make Ubuntu better.

Could you please test the latest upstream kernel available from the very top line at the top of the page from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D (the release names are irrelevant for testing, and please do not test the daily folder)? Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds . This will allow additional upstream developers to examine the issue.

If the latest kernel did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this issue is fixed in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the report description:
kernel-fixed-upstream
kernel-fixed-upstream-X.Y-rcZ

Where X, and Y are two numbers corresponding to the kernel version, and Z is one release candidate number if applicable.

If the mainline kernel does not fix the issue, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-X.Y-rcZ

Please note, an error to install the kernel does not fit the criteria of kernel-bug-exists-upstream.

Once testing of the latest upstream kernel is complete, please mark this report's Status as Confirmed. Please let us know your results.

Thank you for your understanding.

[Neale Upstone (nealeu)]

Wow, that was simple enough (at least it was on my 14.10 install on another partition, where I didn't have virtualbox etc installed).

4.3-wily amd64 packages installed, and bug still exists.

[Neale Upstone (nealeu)]

For anyone interested in the intel backlight. That still doesn't work on 4.3 either, but I've not dug into that.

[penalvch (penalvch)]

Neale Upstone, to clarify the Bug Description:
>"With default boot parameters, I just get /sys/class/backlight/intel_backlight/, and the backlight works correctly on 3.13, but does not change the brightness on 3.16"

Is this when you were using the same nvidia driver version for both tests?

[Neale Upstone (nealeu)]

I haven't tested that original issue (for which I will open a separate bug when I have time to investigate further) against different nvidia drivers.

Given that this issue is about what happens when I do acpi_backlight=vendor, do I need to investigate that for this bug?

[penalvch (penalvch)]

Neale Upstone:
>"for which I will open a separate bug when I have time to investigate further"

You don't have to do that given you were using the same version of the nvidia driver (different versions isn't relevant at this point anyways).

>"Given that this issue is about what happens when I do acpi_backlight=vendor, do I need to investigate that for this bug?"

Well, you shouldn't have to do acpi_backlight=vendor (which is the issue here). Hence, if you remove this parameter and reboot, are you able to change the brightness with the nvidia drivers installed?

[Neale Upstone (nealeu)]

Let's not confuse things. This bug is with Lenovo vendor backlight, and is present on the latest kernel.

The guidance on investigating backlight issues recommends using acpi_backlight=vendor. If neither than nor nvidia or nouveau work, then it really doesn't help the situation. Let's see if we can get what appears to be a relatively simple issue fixed - or else, why bother having the vendor option at all :-|

[Neale Upstone (nealeu)]

I meant "If neither that" btw.

I curse twitter because I cannot correct typos. Launchpad seems as painful.

[penalvch (penalvch)]

Neale Upstone:
>" This bug is with Lenovo vendor backlight"

The bug is not with the Lenovo vendor backlight. It's either a bug in the linux kernel (likely), or a bug in the BIOS.

>"The guidance on investigating backlight issues..."

As is noticed in the guidance, it doesn't tell you to use it forever, but as a debugging step to see if that allows one to change the backlight if one is having an issue with it. This information tells developers where to look within the code to search for a bug depending on the outcome.

Also, you don't need to advise on the contents of the article, given I've contributed towards it as per https://wiki.ubuntu.com/Kernel/Debugging/Backlight?action=info .

Hence, could you please answer the question asked in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1516370/comments/9 ?

[Neale Upstone (nealeu)]

Thanks for the attitude. I wasn't "[advising] on the contents of the article", but trying to be a good citizen in pointing out a bug when I got to the vendor backlight stage of the process.

I still don't see the point of acpi_backlight=vendor then, but as we're not going to be addressing that, then I think this bug should be closed.

I don't have the time to go any further with this, and will open a bug about nvidia drivers if I get that far (as I said).

[Launchpad Janitor (janitor)]

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