8086:0a26 [MacBook Air 6,2] After suspend/resume, screen is dark for brightness levels below 13 with i915 driver

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Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.10 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/v3.10-saucy/

I have also tried without passing the i915.i915_enable_rc6 flag, but the problem persists.

This issue is confirmed as well on Fedora 19 with a Macbook Air 6,2. I have filed a bug upstream based on this information and others.

https://bugs.freedesktop.org/show_bug.cgi?id=67454

Perhaps this is worth commenting on since I'm using similar hardware (Intel HD4000 graphics, Aspire S3-391) but I have the same issue with Kubuntu 13.04, kernel 3.10.4 mainline. This never happened with earlier kernels.

This also happens in newer kernels, at least 3.11, 3.11.1 and 3.12-rc1 are affected.

using "acpi_backlight=vendor" on Saucy.

Before suspend & resume the behaviour of the led-backlight pressing F1 or F2 key is adjustable.
Checking the register `/sys/class/backlight/intel_backlight/brightness` the range from 0 to 2770 can be operated in 21 steps.
After resume still the full range is triggered with the F1 to F2 keys, but here the backlight is turned off completely for all values less than 2280 and fully turned on for all values greater 2290.

Setting the brightness with `echo 2289 > /sys/class/backlight/intel_backlight/brightness` the led backlight starts to flicker in a period of approx 1sec.

DistroRelease: Ubuntu 13.10
Package: linux-image-3.11.0-12-generic 3.11.0-12.19 [modified: boot/vmlinuz-3.11.0-12-generic]
ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.12.5-0ubuntu2
Architecture: amd64
InstallationDate: Installed on 2013-10-17 (1 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: Apple Inc. MacBookAir6,2
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-12-generic.efi.signed root=UUID=77b6a0d2-1d2f-480c-9e22-730bc9b73fed ro pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 acpi_backlight=vendor
RelatedPackageVersions:
 linux-restricted-modules-3.11.0-12-generic N/A
 linux-backports-modules-3.11.0-12-generic N/A
 linux-firmware 1.116

Linus G Thiel, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
DistroRelease: Ubuntu 13.10
InstallationDate: Installed on 2013-10-28 (35 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
NonfreeKernelModules: wl
Package: linux (not installed)
Tags: saucy
Uname: Linux 3.12.2-031202-generic x86_64
UnreportableReason: The running kernel is not an Ubuntu kernel
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip kvm libvirtd lpadmin plugdev sambashare sudo

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This is still an issue even with 3.12.2.
apport-collect won't help here.

beric, in order to track your hardware, please file a new report via a terminal:
ubuntu-bug linux

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Actually, when booting the latest daily from a USB boot disk, the screen brightness seems to work correctly. I'm not sure, because whenever I suspend, it will immediately resume, so I'm not quite sure it's a full suspend.

Linus G Thiel, thank you for your testing. I'm curious, in that as per http://support.apple.com/kb/HT1237 it appears an update is available for your firmware (MBA61.0099.B04). If you update to this does it change anything? If it doesn't, could you please both specify what happened, and provide the output of the following terminal command:
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

Thank you for your understanding.

Hello, i have the same problem and just updated the firmware, but the problem persists!

sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
[sudo] password for cyrofilho:
MBA61.88Z.0099.B04.1309271229
Invalid entry length (0). DMI table is broken! Stop.

09/27/2013
Invalid entry length (0). DMI table is broken! Stop.

Thank you!

Cyro, so your hardware may be tracked, could you please file a new report by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

I have created bug 1266070 with the files you requested from cyro

There are actually two problems:
1) backlight and keyboard light are turn on fully at boot time w/o respecting the original settings. I found the same problem even in single user mode. Turning off KMS with "nomodeset" in grub will preseve the brightness level, but X will go into error.

2) screen backlight becomes only fully on or fully off after suspend as descibed in this bug. This affects 12.04.3, 12.04.4 and 13.10 as I've tried.

There is a work around for the backlight issue.

reference: https://bugs.freedesktop.org/show_bug.cgi?id=67454

>
> To get it running you need to download and build the driver:
>
> # git clone https://github.com/patjak/mba6x_bl
> # cd mba6x_bl/ && make && make install
>
> Make sure the module is loaded at boot time. E.g add "mba6x_bl" to
> /etc/modules
> You also need to configure i915 to hand over the backlight control to
> mba6x_bl. I added this to my /etc/X11/xorg.conf:
>
> Section "Device"
> Identifier "Intel Graphics"
> Driver "intel"
> Option "Backlight" "mba6x_backlight"
> EndSection
>
> Now reboot and you should have working brightness even after suspend/resume.
> Unloading the module (modprobe -r mba6x_bl) will restore the backlight to
> whatever state we had when loading it.

Yuan Chao, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

Hi late to the party on this issue. I have installed 14.04 trusty on my macbook air 6,2 works peachy, however, I did have the issue with my back light when resuming from suspend I have applied the workaround in the following link https://github.com/patjak/mba6x_bl and now everything seems to be operating as expected.

David Haras, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into the default Ubuntu kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs