Bug 539921 - Only dim diplay when power supply changes
Only dim diplay when power supply changes
Product: Fedora
Classification: Fedora
Component: DeviceKit-power (Show other bugs)
i686 Linux
low Severity medium
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Assigned To: Richard Hughes
Fedora Extras Quality Assurance
Depends On:
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Reported: 2009-11-21 11:12 EST by Byron Clark
Modified: 2009-11-25 16:15 EST (History)
2 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2009-11-25 16:15:55 EST
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
Extract percentage using the correct type. (1.39 KB, patch)
2009-11-25 15:16 EST, Byron Clark
no flags Details | Diff

  None (edit)
Description Byron Clark 2009-11-21 11:12:17 EST
Description of problem:
After resume from suspend, the display on my Samsung NC10 frequently dims, even while I am typing.  Continued typing does not raise the brightness.  Sometimes I see an additional icon in the system tray that points to http://blogs.gnome.org/hughsie/2009/08/17/gnome-power-manager-and-blanking-removal-of-bodges/ and says to report a bug to the distribution.

Version-Release number of selected component (if applicable):

How reproducible:
When the dimming happens is not predictable, but it happens frequently after resume.

Steps to Reproduce:
1. suspend
2. resume
3. use computer
Actual results:
Screen won't dim until idle.

Expected results:
Screen dims at random times.
Comment 1 Byron Clark 2009-11-22 08:44:51 EST
This is a little more bizarre than expected.  The screen continues to dim, even when I turn off the "Dim display when idle" checkbox in the "On Battery Power" section of the gnome-power-manager preferences.
Comment 2 Byron Clark 2009-11-23 16:18:53 EST
Watching the output of 'devkit-power --monitor-detail' shows messages like this every time the display dims:

daemon changed:
  daemon-version:  012
  can-suspend:     yes
  can-hibernate    yes
  on-battery:      yes
  on-low-battery:  yes
  lid-is-closed:   no
  lid-is-present:   yes

daemon changed:
  daemon-version:  012
  can-suspend:     yes
  can-hibernate    yes
  on-battery:      yes
  on-low-battery:  no
  lid-is-closed:   no
  lid-is-present:   yes

It appears that the on-low-battery state is changing even though the battery is approximately 80% full.
Comment 3 Byron Clark 2009-11-23 17:40:54 EST
Changed title to reflect what the real problem is.  gnome-power-manager attempts to change the brightness whenever it gets a message from DeviceKit-power showing a change when on-battery is set to yes.  At least on my system these messages happen when the power supply hasn't changed.  I guess the fix would be to get gnome-power-manager to check the last power supply state before attempting to dim or get DeviceKit-power to not send the spurious messages.
Comment 4 Andrew McNabb 2009-11-23 19:17:46 EST
I have a Samsung NC10 and saw the same problem.  There was an auto-dimming setting in the BIOS that I flipped to get rid of the confusing behavior.  It's not really a solution, but it's a pretty good workaround.
Comment 5 Byron Clark 2009-11-24 08:28:32 EST
The BIOS setting Andrew mentions is "Brightness Mode Control".  Setting that to "User Control" instead of "Auto" greatly reduces the frequency at which the screen dims, but it still dims whenever one of those extra change messages comes through.
Comment 6 Byron Clark 2009-11-25 15:16:56 EST
Created attachment 373821 [details]
Extract percentage using the correct type.

The problem was DeviceKit-power using a guint to extract the percentage in the on-low-battery calculation.  The resulting value would be either 0 or -1 depending on the charge percentage.  The attached patch fixes the problem in DeviceKit-power.
Comment 7 Richard Hughes 2009-11-25 16:15:55 EST
Patch applied, thanks.

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