Red Hat Bugzilla – Bug 672778
[kernel] ath5k phy0: gain calibration timeout - wireless connectivity lost until reboot
Last modified: 2012-04-26 19:09:34 EDT
Description of problem:
For the two or three latest 2.6.38 RC kernel builds , driver ath5k exhibits calibration timeouts causing the loss of wireless connectivity. Output of log file /var/log/dmesg shows many trailing lines
"ath5k phy0: gain calibration timeout .." ,
and NM tries repeatedly to reconnect, alas without success.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Boot system.
2. Connect to AP.
NM brings up a wireless connection which only lasts a few minutes.
NM brings up a stable wireless connection.
- Wireless interface is a D-Link DWL-G520 Rev. B4 (Atheros AR2413).
- A system reboot is needed to restore wireless connectivity.
- Upstream bug at https://bugzilla.kernel.org/show_bug.cgi?id=27382 .
- Driver ath5k used to work reliably for kernel-2.6.37-2.fc15.
Reverting successively to earlier kernel builds, it appears that the issue is present from kernel 2.6.38-0.rc2.git1.3.fc15 on, thus
2.6.38-0.rc2.git1.3.fc15 : FAILURE
2.6.38-0.rc2.git1.1.fc15 : SUCCESS
According to the changelog, only a vendor patch has been applied between these two builds:
* Mon Jan 24 2011 Kyle McMartin <kmcmartin redhat com> 2.6.38-0.rc2.git1.3
- Disable usb/pci/acpi autosuspend goo until it can be checked.
After half a day of using kernel 2.6.38-0.rc2.git1.1.fc15, a gain calibration timeout eventually occurred, too, whereas for more recent kernels it happened within a couple of minutes. This observation supports the conjecture of dealing with a genuine 2.6.38 issue.
Created attachment 476753 [details]
Patch for fast channel switch
Patch fixing the fast channel fix issue provided by Nick Kossifis at
Please include it into the next F15 kernel build in order to work around the current issue until it gets fixed upstream. Tge latest kernel-2.6.38-0.rc3.git0.1.fc15 is still affected by this issue making it unusable for people relying on wireless network. Thanks!
I am finding this problem happening again.
I updated my system with yum update on 2012-04-25.
lots of "ath5k phy0: gain calibration timeout" in dmesg
GUI manager allows dis/enabling wireless but shows no networks.
I have not used the wireless for some time, so can't say whether it was broken by recent updates, or has been broken a long time.
I've tried rebooting with kernels from 3.2.10-3 to 3.3.2-6 .
reboots do not help.
Can someone reopen this report?
In my case, emoving the battery restores network connectivity, as reported in similar bugs from 2009, 2010, 2011: