Hardware:
  Com Express module with 1.6GHz core 2 duo processor and 2GB RAM.  Model is COM-840E-L-32 here:
    http://www.adlinktech.com/PD/web/PD_detail.php?cKind=&pid=841&seq=&id=&sid=
  Atheros AR9160 based miniPCI wi-fi module (802.11abgn).  This one:
    http://www.aradasystems.com/product-detail/maxr-953---11a-b-g-n-%28100mw%29/

Linux:
  Ubuntu Server 10.04 64-bit 
  root@ucs-cots2:~# cat /proc/version
  Linux version 2.6.32-23-server (buildd@yellow) (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) ) #37-Ubuntu SMP Fri Jun 11 09:11:11 UTC 2010

  From the kernel map it looks like this is equivalent to 2.6.32.15+drm33.5


Problem:
Linux hangs with no logs when wireless running as AP or Client with ath9k driver.  I don't get the hangs if I disable multi-core processing in BIOS.


Analysis:
It looks like I have this bug (as mentioned in the common problems on the ath9k bugs webpage: http://wireless.kernel.org/en/users/Drivers/ath9k/bugs).

  "Hangs with PCI devices and SMP systems"

The implemented fix is not picked up for my device (an AR9160 basic miniPCI card) as seen from the following debug output:

    kernel: [   52.962332] ath9k: serialize_regmode is 0

I compiled the latest stable version of ath9k (compat-wireless-2.6.35-rc4) using compat-wireless and still got the same problem.

I 'shoe-horned' the fix into the compat-wireless-2.6.32.16 driver by adding the following line to HW.C:

        if (ah->config.serialize_regmode == SER_REG_MODE_AUTO) {
                if (ah->hw_version.macVersion == AR_SREV_VERSION_5416_PCI ||
                    (AR_SREV_9280(ah) && !ah->is_pciexpress)) {
                        ah->config.serialize_regmode =
                                SER_REG_MODE_ON;
                } else {
                        ah->config.serialize_regmode =
                                SER_REG_MODE_OFF;
                }
        }
 
        #### New line to force serialisation to ON ####
        ah->config.serialize_regmode = SER_REG_MODE_ON;

        DPRINTF(ah->ah_sc, ATH_DBG_RESET, "serialize_regmode is %d\n",
                ah->config.serialize_regmode);

This forces serialisation on:

    kernel: [   61.449975] ath9k: serialize_regmode is 1

and fixes my issue - I no longer see hangs.

Is it possible to get the fix expanded to cover AR9160-based devices?

Thanks.