[ath9k-devel] D-Link DWA-547 completely freezes system

[Luis R. Rodriguez <lrodriguez@atheros.com>]

On Fri, Jan 22, 2010 at 09:52:14AM -0800, Pavel Roskin wrote:
> On Fri, 2010-01-22 at 10:58 +0100, Khashayar Naderehvandi wrote:
> 
> > > I can confirm that 0xdeadbeef comes from the chip, not from some random
> > > place in memory.  Even the supported Ubiquiti SR71-15 returns 0xdeadbeef
> > > when reading from the register 0x00ac (AR_IMR_S2).
> > >
> > > The fact that SR71-12 only works if installed in a slot below SR71-15 is
> > > very intriguing.  I checked the modules with nm for possible static
> > > variables, but I cannot spot anything wrong.  I'm going to try
> > > mmiotrace.
> > >
> > Pavel, this is way too technical for me to understand :)
> 
> Sorry, it was meant for Luis.
> 
> Ubiquiti SR71-15 is the only AR9220 card I know that works with ath9k.
> It's a 5GHz-only card, so maybe that's the reason.

We actually hadn't sold 5 GHz only cards like that, I think Ubiquity
choose to customize the hardware.

> Ubiquiti SR71-12 is a 2GHz card and it doesn't work.

And not sure if this is something custom too. I'm checking internally.

> However, if
> SR71-15 is present in the same system and has a lower PCI address so
> that it's initialized first, SR71-12 would work.  This makes me think
> that the initialization of SR71-15 changes something in the state of the
> driver.  The state should be separate for every device, so it may be a
> bug.

Openwrt folks were the ones who added 5 GHz only support recently and
that was ubiquity in mind. Its unclear to me if the 2 GHz only AR9220
you are seeing is something custom too.

> I discovered that reading from some registers gives 0xdeadbeef.

AR9220 would be treated as dual band all the time, I think if all the 5 GHz
stuff is skipped for this particular device perhaps it should work OK, but
that is just theory.

  Luis