light sensor misjudge ambience light

Bug #1322396 reported by Zhang Weiwu on 2014-05-23
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Medium
Unassigned

Bug Description

Running Ubuntu 14.04 on bModo12 (same hardware as WeTab). When running on battery, the screen changes brightness frequently, by itself, while there are little change in ambience light. In fact, if I just place it stablly on the table and observe from distance, it turns bright and dark all by itself happyly, once a few seconds. It is unbearable to use.

I installed brightness control applet "indicator-brightness", and hoped manual control overwrites automatic ambience light sensor. But no, automatic sensor overwrites manual setting. If I set brightness to 10, for example, it is bright for one second, and back to darkness.

I urgenly need a workaround - a method to turn off light sensor and force always brightest light output. Kindly offer a workaround before solving this bug. Thanks!

My hardware and system is the same when I reported bug 1318639 - and the bug always exists since I installed the OS in day 1.
Inform me if you insist on a new machine-generated PC/OS information set.

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

apport-collect 1322396

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.

Changed in linux (Ubuntu):
status: New → Incomplete
Joseph Salisbury (jsalisbury) wrote :

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-rc7-utopic/

Changed in linux (Ubuntu):
importance: Undecided → Medium
Zhang Weiwu (zhangweiwu) wrote :

tested on 3.15.0-031500rc5-generic. The censor still misjudge ambience light, and flickers the screen when there are no noticable light change.

tags: added: kernel-bug-exists-upstream
Changed in linux (Ubuntu):
status: Incomplete → Confirmed
Zhang Weiwu (zhangweiwu) wrote :

Can anyone provide a workaround first? For example how to prevent light sensor from working at all, disable the module or kernel feature that uses it.

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