[ltp] Re: Interference of wlan usage and hdaps?

[Henrique de Moraes Holschuh]

On Tue, 22 Sep 2009, Elias Oltmanns wrote:
> Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> > On Tue, 22 Sep 2009, Elias Oltmanns wrote:
> >> The rather annoying result of it all is that hdapsd frequently parks the
> >
> >> disk heads, sometimes preventing all I/O for tens of seconds without
> >> interruption. Clearly, this strange behaviour only occurs once I have
> >> connected to my wlan and goes on persistently afterwards, irrespective
> >> of the current state of the wlan interface.
> >
> > Is it a function of the interrupt handling of the kernel driver (i.e. normal
> > behaviour is restored if you rmmod the kernel driver for the wlan card), or
> > of the hardware itself?
> 
> Well, I have done very little testing on the current machine yet, but
> the problem persisted even after unloading the driver last time. Still,
> after my experience with the atheros driver, I am inclined to believe
> that this is a software issue and probably very similar too. It may, of
> course, be hidden in the binary firmware image loaded by the hotplug
> agent.

It is possible that the accelerometer is not properly shielded in the X40,
and once the WLAN card is put in D0, it starts borking.  Try hacking the ipw
driver to put the WLAN card in D3 on rmmod, maybe that would cure hdaps :-)

>From what I recall, the firmware hdaps interface is really horrible, but it
is not supposed to go crazy because of some added latencies or time spent in
lala-land with interrupts disabled.

UNLESS the SMBIOS gets in the way.  Then, all bets are off.  Make sure
you're at the latest BIOS and EC firmware on the X40.

> remains though, ath5s has to be fixed. And now I rather suspect that the
> same applies to ipw2200 or the firmware.

Well, the ipw2200 firmware runs entirely in the ipw2200/2950 card :p  There
is no binary blob that runs in the host CPU.  So, it should be fixable if it
is taking a walk in the park with interrupts disabled...

> > Well, I have never seen anything like it in my T43 with an IPW2950 wlan
> > card.
> 
> Interesting, perhaps I'm barking up the wrong tree after all.

Maybe you're at the correct tree.  It is early to tell :)

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh