Bug 19736 - synaptics driver causes a lot of cpu wakeups
Summary: synaptics driver causes a lot of cpu wakeups
Status: RESOLVED NOTOURBUG
Alias: None
Product: xorg
Classification: Unclassified
Component: Input/synaptics (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: medium normal
Assignee: Peter Hutterer
QA Contact:
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Depends on:
Blocks:
 
Reported: 2009-01-25 11:28 UTC by Jostein Bø Fløystad
Modified: 2009-02-01 14:56 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
Output from powerto -d with touchpad movement (3.63 KB, text/plain)
2009-01-25 11:33 UTC, Jostein Bø Fløystad
no flags Details
Output from powerto -d without touchpad movement (3.53 KB, text/plain)
2009-01-25 11:34 UTC, Jostein Bø Fløystad
no flags Details

Description Jostein Bø Fløystad 2009-01-25 11:28:36 UTC
Using powertop to monitor cpu wakeups on a laptop on battery (my case: thinkpad t400), the number of wakeups rises for the "PS/2 keyboard/mouse/touchpad" from less than five to around 400 hundred or more (resulting in a rise in power consumption of 2-3 Watts in most cases -- quite significant on a laptop) when the touchpad is used.

How to reproduce: Start powertop as root when the machine is idle and wait for it to stablize it's measurements. Then move the pointer around a lot, and wait for powertop to refresh its readings. The same effect is not seen while typing.

The same issue has also been reported elsewhere:

Ubuntu bug report:
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/+bug/194489

Arch linux forum thread:
http://bbs.archlinux.org/viewtopic.php?pid=486690

As the same appears on different distributions and kernel versions, it is likely to be caused by the driver, although I can't be sure.

My system specs:
Lenovo Thinkpad T400
Synaptics touchpad (part of an UltraNav)
Arch Linux x86_64
version 0.99.3 of xf86-input-synaptics
Comment 1 Jostein Bø Fløystad 2009-01-25 11:33:18 UTC
Created attachment 22229 [details]
Output from powerto -d with touchpad movement
Comment 2 Jostein Bø Fløystad 2009-01-25 11:34:34 UTC
Created attachment 22230 [details]
Output from powerto -d without touchpad movement
Comment 3 Peter Hutterer 2009-02-01 14:56:19 UTC
From the original bugreport:

"powertop reports a huge amoun of wakeups from the touchpad. Notice that this is independent of the synaptics driver being loaded or not. I get the exact same results with an out of the box xorg.conf where the touchpad is recognized as a plain mouse. The screenshot shows the problem."

This is a kernel issue, not one of the X.Org synaptics driver -> NOTOURBUG.


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