[CUWiN-Dev] Re: ath0: hardware error
David Young
dyoung at pobox.com
Tue Aug 30 18:17:29 CDT 2005
On Mon, Aug 29, 2005 at 07:18:28PM -0500, David Young wrote:
> On Mon, Aug 29, 2005 at 06:27:12PM -0500, Bill Comisky wrote:
> > On Mon, 29 Aug 2005, Bill Comisky wrote:
> >
> > >On Thu, 25 Aug 2005, David Young wrote:
> > >
> > >> On Thu, Aug 25, 2005 at 03:29:16PM -0500, Bill Comisky wrote:
> > >>> On Sun, 21 Aug 2005, David Young wrote:
> > >>>
> > >>> > I added some debug messages as I tried to track down the source of
> > >>> > "ath0: hardware error; resetting". The debug messages have not shown
> > >>> > me any obvious problem, but they do seriously slow down some nodes,
> > >>> > so I am taking them out.
> > >>> >
> > >>> > Apply these patches to your NetBSD sources. They take out the noisy
> > >>> > debug messages:
> > >>> >
> > >>> > Apply ath-undo-1 in sys/dev/ic/, ath-undo-2 in sys/dev/:
> > >>> >
> > >>> > % cd your-netbsd-sources/src/sys/dev/ic
> > >>> > % patch < ath-undo-1
> > >>> > % cd -
> > >>> > % cd your-netbsd-sources/src/sys/dev
> > >>> > % patch < ath-undo-2
> > >>> >
> > >>> > Dave
> > >>>
> > >>> Should I be seeing any "ath0: hardware error..." messages after these
> > >>> patches have been reverse applied? I'm still seeing them, sometimes a
> > >>> lot
> > >>> of them. I can see the CPU "% interrupt" in top shoot up when they're
> > >>> spewing to about 60% (with hw.ath0.debug=0x80000000 commented out in
> > >>> sysctl.conf). I feel like my build broke somehow, though I deleted the
> > >>> build directory and unpacked the source fresh before "patch -R".
> > >>
> > >> You may still see "ath0: hardware error...", but they should not come
> > >> with the Rn and Tn lines that you used to see.
> > >>
> > >> I don't know what causes ath0: hardware error. The author of the driver
> > >> tells me that I may need a PCI bus analyzer to figure it out. :-(
> > >>
> > >> I am a PCI novice, but I strongly suspect that the error has something
> > >> to do with PCI bus contention:
> > >>
> > >> 1) I get a lot more "ath0: hardware error" indications on my Soekris
> > >> net4521 when it carries one or two Cardbus WiFi cards in addition to
> > >> the MiniPCI Atheros card. I scarcely get any such indications when the
> > >> MiniPCI cards are not in there.
> > >>
> > >> 2) The madwifi driver (Linux version of ath, also by
> > >> Sam Leffler) sets an unusually large PCI Latency Timer,
> > >> <http://cvs.sourceforge.net/viewcvs.py/madwifi/madwifi/ath/if_ath_pci.c?only_with_tag=HEAD&view=markup>.
> > >>
> > >> Madwifi may also set some other parameters differently from NetBSD,
> > >> which accepts defaults---I will check a little later.
> > >>
> > >> 3) A discussant at
> > >> <http://www.broadbandreports.com/forum/remark,9086546~mode=flat> mentions
> > >> that changing his PCI Latency Timer from 32 to 64 helped prevent some
> > >> system lockups when his Atheros card was activated.
> > >>
> > >> 4) The Soekris BIOS does not set PCI minimum grant, maximum latency,
> > >> or latency timer that make any sense according to the explanation given
> > >> at <http://www.reric.net/linux/pci_latency.html>.
> > >>
> > >> Bill, will you do me a favor, and send me both dmesg(8) and pcictl(8)
> > >> output for your Atheros card? Here is how I got the pcictl info I
> > >> wanted:
> > >
> > >Dave,
> > >
> > >After many upgrade/reboot cycles, I've found out a few things about the
> > >ath0 errors I'm seeing. I found that only our local builds with our local
> > >modifications were going into the endless "ath0: hardware error" loop.
> > >After some more experimenting, I found that the changing the SSID can
> > >trigger these errors. We had changed our local cuw_config_ssid setting to
> > >'cntwireless.net', and those builds were getting ath0 errors as soon as
> > >the devices were brought up. I found I could set off the errors and stop
> > >them by calling 'ifconfig ath0 ssid' with a new SSID from the command
> > >line. 'cuwireless.net' or anything of the same length always seems ok,
> > >anything longer triggered the errors. Sometimes smaller SSIDs would
> > >trigger the error as well; though it seemed to depend on what you were
> > >changing from. Sometimes the same SSID would cause the error and sometimes
> > >not, depending on what you were changing from. Perhaps some important
> > >chunk of memory is being written over somewhere? The repeatability of
> > >errors at boot time wasn't 100%; occasionally (maybe only on 1st reboot
> > >after an upgrade?) I would get results that confounded my expectation
> > >(errors when not expecting them, or no errors when expecting them).
> > >
> > >My first set of experiments I did on source with the ath_undo patches
> > >reverse applied. In this case, I either got no console messages when
> > >switching SSIDs (to cuwireless.net for example), or I got repeated groups
> > >of the following when changing to a "bad" ssid, such as cntwireless.org:
> > >
> > >ath0: hardware error; resetting
> > >ath_stoprecv: rx queue 0x10f14fc, link 0xc5dff4d0
> > >[followed by a bunch of R0 lines]
> > >
> > >To make sure it wasn't something with our build process or source, I
> > >downloaded and installed the CUWiN 0.5.8 release; which I don't think has
> > >the ath_undo patches. In this case, I got ath0: console messages (with
> > >more stuff than above, see attachments) whenever I set the SSID, but the
> > >"bad" cases set of an endless loop of these messages. When I repeated the
> > >experiments on a net4526 (had been working on a net4511), I couldn't
> > >reproduce the endless loop. I've attached files with console dumps of
> > >these last experiments showing dmesg, pcictl dumps, and the output from
> > >"ifconfig ath0 ssid". I noticed that the radio firmware had a different
> > >version 3.6 vs. 4.6 for the two radios I used from the dmesg output, so I
> > >repeated the net4526 experiment after switching the radio. I still didn't
> > >get the endless stream of ath0 errors. For all of these tests, there were
> > >no other nodes up.
> > >
> > >Can you reproduce the repeated ath0: errors on a net4511 with a "ifconfig
> > >ath0 ssid somebigssidhere"? Does this give you any clues as to where the
> > >problem may be?
> >
> > An addendum: With my local build (with ath_undo patches and some
> > customizations) I do see the same stream of ath0: hardware errors on the
> > net4526. I can stop them by setting the SSID to cuwireless.net and start
> > them by setting it to something longer.
>
> Great work!
>
> Perhaps "ath0: hardware error; resetting" is caused by Tx FIFO underruns
> during beacon transmissions. That would fit some of the evidence.
> We would be worse off with a longer SSID (makes a longer beacon) than
> with shorter SSIDs. Underruns could be connected with bad PCI setup,
> which would tend to delay or fragment PCI bus transfers.
I was able to semi-reliably reproduce the lossage you report with
'ifconfig ath0 ssid cntwireless.net'. I have attached a patch I applied
that may have fixed the problem.
I see a lot of these messages scrolling up the console when I set ssid
cntwireless.net. No doubt it's because the SSIDs don't agree. I remember
you mentioned that before. I will send a second patch that quiets things.
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
ieee80211_ibss_merge: merge failed, capabilities mismatch
Dave
--
David Young OJC Technologies
dyoung at ojctech.com Urbana, IL * (217) 278-3933
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