8086:4229 iwlagn: Received BA when not expected

I would like to confirm the issue is present in Ubuntu 11.04 amd64 (Linux kernel 2.6.38-8) with Intel Link 6250 WiFi/WiMAX card and the latest version of microcode from Intel. In my case both kern.log and syslog are flooded with "Received BA when not expected" messages.

The issue is most likely within the microcode for some Intel WiFi cards supporting 802.11n since it had been reported in other Linux distributions as well, for example over there:
https://bugzilla.redhat.com/show_bug.cgi?id=646082
The proposed workaround was to modify iwlwifi options in /etc/modprobe.d/iwlwifi.conf

echo "options iwlagn 11n_disable50=1 11n_disable=1" >>
/etc/modprobe.d/iwlwifi.conf

Update to comment #2:

While 802.11a,g seems works stable in my system, connecting via 802.11n results in flooding log files with "Received BA when not expected" messages. The speed of local connection to the router is unstable and can vary between 19 to 58 Mb/s (which is still way above my ADSL bandwidth).

To add more to the issue, firmware restart occurs periodically (see firmware.error.txt attached below). On some occasions of heavy network traffic yet another kind of firmware crash happens sometime (firmware.error.1 and 2 attached).

My system is based on Toshiba Satellite L40 series laptop with wireless upgraded to Intel Link 6250 ANX WiFi/WiMAX,
Ubuntu 11.04 amd64 (Linux kernel 2.6.38-8) and WiFi firmware version 41.28.5.1 (build 33926). Wireless connection is via router Buffalo NFiniti WHR-G300N-V2.

I can confirm this happening on a Dell Latitude E6500 with the following wifi:
0c:00.0 Network controller: Intel Corporation WiFi Link 5100

I'm seeing the same messages, and am getting extreme latency spikes (>8000ms within the local network) as well as packet loss > 60%.

The proposed workaround helps - the connection throughput is much slower than it should be, but at least it is stable with acceptable latency and no packet loss.

Since a patch from an upstream kernel release v2.6.39-rc5-274-g609cfda (see https://bugzilla.kernel.org/show_bug.cgi?id=16691) was backported into the latest Ubuntu kernel v2.6.38-10.44, I have not experienced any "Received BA when not expected" issue by now. Now, with 802.11n support turned back on, my connection to the router is stable with a speed of circa. 130 MBit/s. What's more, all crashes of the second type I have reported above (Firmware crash 2) have gone completely. The overall system performance is back to normal again.

However, on some rare occasions crash of the first type (Firmware crash 1) still occurs. Having no noticeable effect on the system performance, it seems to be a pure microcode issue and should be reported upstream to microcode developers. An example is attached below.

I am running Ubuntu 10.04 64 bit on a Dell Latitude E6510 and this error is flooding my syslog file.

lspci -v:

02:00.0 Network controller: Intel Corporation WiFi Link 6000 Series (rev 35)
               Subsystem: Intel Corporation Device 1321
               Flags: bus master, fast devsel, latency 0, IRQ 33
               Memory at f0400000 (64-bit, non-prefetchable) [size=8k]
               Capabilities: [c8] Power Management version 3
               Capabilities: [d0] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
               Capabilities: [e0] Express Endpoint, MSI 00
               Capabilities: [100] Advanced Error Reporting <?>
               Capabilities: [140] Device Serial Number 28-45-85-ff-ff-14-23-00
               Kernel driver in use: iwlagn
               Kernel modules: iwlagn

Ralf Hildebrandt, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this 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 please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

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

Also, could you please test the latest upstream kernel available? It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please do not test the kernel in the daily folder, but the one all the way at the bottom. 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. As well, please comment on which kernel version specifically you tested.

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', and comment as to why specifically you were unable to test it.

Please let us know your results. Thanks in advance.

Helpful Bug Reporting Links:
https://help.ubuntu.com/community/ReportingBugs#Bug_Reporting_Etiquette
https://help.ubuntu.com/community/ReportingBugs#A3._Make_sure_the_bug_hasn.27t_already_been_reported
https://help.ubuntu.com/community/ReportingBugs#Adding_Apport_Debug_Information_to_an_Existing_Launchpad_Bug
https://help.ubuntu.com/community/ReportingBugs#Adding_Additional_Attachments_to_an_Existing_Launchpad_Bug