On Sun, 08 Apr 2012 12:59:21 +0200
Soren Kristensen <[email protected]> wrote:

> Attila Kinali wrote:
> > You repeat this argument over and over. But apearently, you are the only
> > one who knows about these race conditions. I cannot find any reference
> > to the race condition on the VT6105M at all. And for the ath9k race,
> > the only one i could find was fixed october 2010 in the mainline kernel.
> > Can you provide us with references to what race conditions you mean and
> > where they are to be found?
> 
>  From my post on 12/7/2011:
> 
> Looking though the archieves I found two reported issues, both on Linux.
> 
> 1) The thread in Sept/Oct 2010, concluding with Andrey Safonov reporting 
> the Linux VIA VT6105M driver to have bug, and how to fix it:
> 
> http://lists.soekris.com/pipermail/soekris-tech/2010-October/016884.html
> http://lists.soekris.com/pipermail/soekris-tech/2010-October/016889.html

I cannot tell whether this has been fixed or not. The via-rhine driver
irq handling has seen a big overhaul since then. It could be that it's
fixed, it could be that it's not. Unfortunately, the reporterd did not
mention which kernel version he was using, hence i cannot even check
whether the code path is now properly locked or not, as i can only guess
what changes he did exactly (a proper patch would have been helpfull)

 
> 2) And "green" reporting a fix to either ath9k, or all wireless drivers, 
> in his post on Jan 25, 2011:
> 
> http://lists.soekris.com/pipermail/soekris-tech/2011-January/017001.html

Here again, no mention of the kernel version that has been used.
It could very well be that this is the race condition i found which has
been fixed in oct 2010. Please note that "compat-wireless" is the development
version of the wifi driver team, released for the benefit of those who
do not want to wait for the mainline kernel to pick up the changes they did.

As i said, my kernel has the version 3.2.1, which is has been released
on Jan 12, 2012. This is considerably newer than any of those reports.
I am sure that the ath9k bug has entered mailine kernel since then
(they sync up on ever second kernel release at least). And the other one
probably too if it has been properly reported to the kernel developers.


> > Soren, if you really have an explenation how a software bug (a race
> > condition as you say) can be fixed with a soldering iron, i really like
> > to hear that. I have systems that experience race conditions under
> > every once in a while and i'd like to fix those as well with my soldering
> > iron.
> 
> Attila, thanks for the detailed testing done. I agreed with you that 
> adding capacitors should not change behavior if it's a software problem 
> alone.

Finally you believe me....
 
> I will still state that the net5501 has the decoupling it needs for 
> itself and the expansions it's designed for. One possible sources of 
> problem could be the power supply regulators as they located just behind 
> the mini-PCI slot, RF could be affecting t.ex. the compensation circuit, 
> so adding decoupling capacitors just fix the symptoms.

Could be. I think that's unlikely. I rather think that the wlan card
has a spiky power need, probably drawin ~300mA for very short periods.
The VIA6105M should have about the same spikyness, but with less power
consumption. As both share their power supply vias and capacitors, it's
only a matter of time that both spike at the same time, moving one or
both subsystems into a operating condition outside the specs.

> I would also like to investigate the problem further. Can you please 
> tell me the exact wlan card ?

I bought the following from soekris.eu:

Complete wireless Bundle 9220-2
Power Supply, 12V, 3.0A, IEC320-C8 inlet 90V-264V Worldwide
2.5" SATA hard drive mounting kit for the net5501
net5501-70 Board and 1 Slot standard Case

Please not that i had to use different antennas, as the net5501 has
no space to drill holes for the TNC connectors. Why you sell them
together is beyond me...

> And can you please ensure that the vt6105 driver is updated to a fixed 
> one, would really love data after that is done....

As i said, i cannot. But i'm using a pretty recent kernel. If it
isn't fixed yet after 2 years...

> I still have the problem that nobody running FreeBSD and OpenBSD have 
> reported similar issues, somebody correct me if I'm wrong.

Have you considered that it might be because there are many more people
using linux than *bsd? Hence reports with linux are much more likely.

                        Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?
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