FS#18982 - [kernel26] 2.6.33 Plugging or unplugging notebook's charger renders Atheros card unsuable
Attached to Project:
Arch Linux
Opened by Mauro Santos (R00KIE) - Tuesday, 06 April 2010, 20:58 GMT
Last edited by Andrea Scarpino (BaSh) - Saturday, 16 April 2011, 11:01 GMT
Opened by Mauro Santos (R00KIE) - Tuesday, 06 April 2010, 20:58 GMT
Last edited by Andrea Scarpino (BaSh) - Saturday, 16 April 2011, 11:01 GMT
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Details
Description:
Unplugging or plugging the notebook's charger will make the Atheros wireless card unusable if a scan is issued, as in changing the notebook from one place to another, loosing the connection to the access point and scanning for available access points. The card will remain unusable until the machine is powered off and on again, rebooting will not make the card work again. I can trigger this problem with all of arch's kernels from 2.6.32.9 to the latest 2.6.33.2 in [testing]. I have found that this problem is easier to trigger with newer kernel versions. I have also tried using madwifi and ndiswrapper and I can still trigger this problem. It doesn't seem to be a problem with rfkill because after the card become unusable it still says everything is unblocked. Steps to reproduce: 1) Turn on the machine with the charger plugged in and bring the network up with 'ifconfig wlan0 up', no association with the access point is needed to trigger the problem. 2) Issue a scan with 'iwlist wlan0 scan', the results are almost the expected results apart from the signal strength (see file wlan0_scan_1). If another scan is issued (see file wlan0_scan_2) then everything seems normal and it is still possible to associate with the access point. No errors or warnings are issued. 3) Unplug the notebook charger. 4) Issue another scan, this time no access point is detected (see file wlan0_scan_3) and there are errors in dmesg about "gain calibration timeout" (see file dmesg_after). No other errors are issued as far as I can see. This problem also happens if the sequence is booting the machine on battery, performing steps 1) and 2), then plugging the charger and performing step 4). I have asked in the forum [1] if anyone had any ideas but none of the suggested solutions worked for me. I've reported this upstream [2] but as this is such an odd problem it is hard to believe, even I though the card was half toast until I got things to work fine with kernel 2.6.32.8. [1] http://bbs.archlinux.org/viewtopic.php?id=93450 [2] https://bugzilla.kernel.org/show_bug.cgi?id=15693 
wlan0_scan_1
(1.1 KiB)
wlan0_scan_2
(1.1 KiB)
wlan0_scan_3
(0 KiB)
dmesg_after
(34.5 KiB)
lspci_vvv
(30 KiB)
modules
(4.4 KiB)
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This task depends upon
Closed by Andrea Scarpino (BaSh)
Saturday, 16 April 2011, 11:01 GMT
Reason for closing: Fixed
Additional comments about closing: kernel26 2.6.38.2-1
Saturday, 16 April 2011, 11:01 GMT
Reason for closing: Fixed
Additional comments about closing: kernel26 2.6.38.2-1
I can scan all I want if I don't change the power state.
It doesn't matter if I turn the notebook on with it plugged and then unplug it or if I turn
it on using the battery and then plug it.
I have discovered the problem is related (in my case) with having the module powernow_k8 loaded. There is no need to load any cpufreq*
modules or even change the cpu governor, just loading powernow_k8 is enough to be able to trigger the problem.
I have an AMD cpu in my notebook and I have found that if I use phc-k8 [1] instead of powernow-k8 then
wireless works fine and I still have cpu frequency scaling. If anyone has an INTEL cpu and is also affected,
phc-intel [2] might be worth a try (if the problem is connected with modprobing the cpu driver).
[1] http://aur.archlinux.org/packages.php?ID=22953
[2] http://aur.archlinux.org/packages.php?ID=24980
Is it still a problem?
Upgraded to 2.6.38.2-1 and everything works just fine.