[Lenovo ThinkPad X230] LCD Backlight dims completely when disconnecting external monitor

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Dustin Lundquist, could you please test the latest upstream kernel available (not the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-3.15-rc3

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

I've also had this happen on my Thinkpad T420.

This is happening on my T420s running 3.13.0-29

I am happy to test bisected kernels

Yaiza Bailen, 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

Hi Cristopher,

That was already done here:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1276037

But marked as duplicated under this one.

Thanks,
Yaiza

Yaiza Bailen, no it was not, as you are not the original reporter of 1276037.

Hi Cristopher, I wasn't the reporter of 1276037 but the laptop was the same. In any case I just filled in a new bug.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1342053

It's too hard to reproduce this bug because I have not the same hardware.
I have tested it on three types of laptop, but can't reproduce this bug. They are:

1. T540P with Displayport monitor
2. T440s with Displayport monitor
3. x230S with Displayport monitor. We have no external dock to touch DVI monitor.

All the laptop are installed with ubuntu 14.04 and the kernel is 3.13.0-24-generic.
I note that Yaiza Bailen has the bug on T420 and T420s with Displayport monitor, which may be
similar with my #2 laptop, but it can't be reproduced.
It seems that I need to get the same hardware to reproduce the bug.

hi, @dlundquist , Dustin Lundquist,
Did you test it on x230 with DisplayPort monitor?
Or it only existed when x230 is plugged with DVI on the dock?
Whether can following command change the brightness of LCD?

$ echo 100 | sudo tee /sys/class/bachlight/acpi_video0/brightness

or

$ echo 600 | sudo tee /sys/class/backlight/intel_backlight/brightness

Hi,

If I log out and log in again, the brightness is recovered.

This also affects 2nd generation (Haswell) X1 Carbons when unplugging a DisplayPort monitor. Kernel version 3.13.0-32-generic.

Yaiza Bailen / Danny Yates, 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

Po-Hsu Lin helped to test on a x230s, could not re-produce the issue:
========================

On 2014年07月24日 10:56, Po-Hsu Lin wrote:
> Hello,
> I've verified this on our x230s here, it cannot be reproduced.
>
> Steps:
> 1. Install 14.04, boot to desktop
> 2. Connect a external DP monitor
> 3. Disconnect it, check the brightness
> 4. Connect a external D-Sub monitor
> 5. Disconnect it, check the brightness
>
> Cheers

Hi Christopher. Sorry for the delay, but it turned out I wasn't subscribed to this bug. I have created a new bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1353429 to track my hardware and subscribed you to it as requested.

Thanks.

I am also experiencing this problem with a Lenovo T440s.

Linux quickstone 3.13.0-34-generic #60-Ubuntu SMP Wed Aug 13 15:45:27 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

This seems to be a regression, that had happened not long ago.

Currently I am experiencing this bug with 3.13.0-44-generic (backported to Ubuntu 12.04) on a T420s. It applies to the VGA port too.

However, I used external displays from time to time, and do not experience this bug about two month ago. So for me, it appears to be added by the last two moths. However, the backported kernels may be a little delayed, so others may experience this bug earlier this year.

Xaq Rothman / dronus, thank you for your comment. So your problem and hardware 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
https://wiki.ubuntu.com/Kernel/Policies/DuplicateBugs
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.

As well, please do not announce in this report you created a new bug report.

Thank you for your understanding.

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

Still happens on T420s with 3.13.0-51-generic . All symptoms exactly the same.