Wireless connection only works fine when wall powered

Bug #714163 reported by ginosal on 2011-02-06
This bug affects 3 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

Binary package hint: acpi

Hi. My wireless connection works very well with Windows 7 on this Acer laptop. On Ubuntu, i was experiencing some problems (unstable connection). Some web pages were very difficult to load on Ubuntu 10.4, so I upgraded to 10.10. It seemed to be working fine, but it was because the laptop was powered by wall power and not by battery. When I disconnect AC power, my connection becomes unstable again.

My Network controller is: " Atheros Communications Inc. AR9287 Wireless Network Adapter (PCI-Express) (rev 01)".

The Kernel is: 2.6.35-26-generic

To be more precise: Network manager always displays my connection as working, but when my laptop is battery powered, some sites are very slow or unreachable (connection is timed out).

I can add the result of lsmod | grep ath, someone says there could be a module conflict:

lsmod |grep ath
ath9k 111737 0
mac80211 278659 1 ath9k
ath9k_common 3151 1 ath9k
ath9k_hw 288136 2 ath9k,ath9k_common
ath 17109 2 ath9k,ath9k_hw
cfg80211 166442 3 ath9k,mac80211,ath

Please help me! Thank you in advance.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: acpi (not installed)
ProcVersionSignature: Ubuntu 2.6.35-26.46-generic
Uname: Linux 2.6.35-26-generic x86_64
Architecture: amd64
Date: Sun Feb 6 18:25:35 2011
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
SourcePackage: acpi

ginosal (driver-8) wrote :

I've shifted to OpenSUSE and with OpenSUSE my wireless connection works fine, with or without wall power. Maybe this could help you to understand the reasons of the malfunctioning, by confronting the acpi settings in Ubuntu and those used in OpenSUSE. Please, work on it if you can, because OpenSUSE is good, but Ubuntu is better :)

Jessica K. Litwin (press5) wrote :

I'm also experiencing this issue using xubuntu - since it is a derivative of ubuntu it makes sense that it appears there also.

It appears this is related to overzealous power management for the wireless card when on battery; on my system the wireless card is eth1 and it's power management setting on battery is 'All packets received'. Switching it off by issuing a ' iwconfig eth1 power off' will fix the issue, and doing something like

/sbin/iwconfig eth1 power off

and saving it as /etc/pm/power.d/wireless will fix it across reboots. There may be better ways to accomplish this whilst still retaining some power management, but this will restore functionality.

I agree that there should be some level of power management to help preserve battery life, but the current behavior of power management for wireless cards has a crippling effect on battery power. I consider it a rather critical bug, and suggest that it be addressed as such and a fix pushed out as an update quickly.

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in acpi (Ubuntu):
status: New → Confirmed
Jessica K. Litwin (press5) wrote :

s/crippling effect on battery power/crippling effect on wifi speed/

jbeezo (jbeezo) wrote :

I'm very surprised to see such a low heat level on this ticket. With my newish Acer AS5750 I enabled ACPI so that I could enable screen dimming (since it wasn't working as expected). Then once unplugged from the wall socket Wifi quit completely (BCM43227). Makes portability pretty useless!! Luckily I found the following blog post: http://uselessuseofcat.com/?p=67

ginosal, thank you for reporting this and helping make Ubuntu better. Maverick reached EOL on April 10, 2012.
Please see this document for currently supported Ubuntu releases:

We were wondering if this is still an issue in a supported release? If so, can you try with the latest development release of Ubuntu? ISO CD images are available from http://cdimage.ubuntu.com/releases/ .

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

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

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text.

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'.

Please let us know your results. Thanks in advance.

affects: acpi (Ubuntu) → linux (Ubuntu)
Changed in linux (Ubuntu):
status: Confirmed → Incomplete
tags: added: needs-upstream-testing
Changed in linux (Ubuntu):
importance: Undecided → Medium
Launchpad Janitor (janitor) wrote :

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

Changed in linux (Ubuntu):
status: Incomplete → Expired
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