Re: [PATCH] ath9k: Fix PCI FATAL interrupts by restoring RETRY_TIMEOUT disabling

[Jouni Malinen <j@w1.fi>]

On Tue, Jun 16, 2009 at 10:33:29AM -0400, Bob Copeland wrote:
> > An earlier commit, b572b24c578ab1be9d1fcb11d2d8244878757a66, removed
> > code that was documented to disable RETRY_TIMEOUT register (PCI reg
> > 0x41) since it was claimed to be a no-op.
> 
> Jouni, can you confirm that e23a9014... also needs reverting?
> (In this case only affects resume path).

I wish I could, but I can only guess that it probably should be
reverted.

> I seem to remember the provenance of this code was copy-paste from
> an intel driver, so while it does "something," the comment may not
> match the code, 0x41 being vendor-defined.

The exact story behind this has been a bit more than trivial task to
figure out ;-). I would assume this comment is referring to a madwifi
changeset: http://madwifi-project.org/changeset/584

I've yet to find documentation that would explain the exact meaning of
PCI register 0x41 in case of ath9k/ath5k-supported devices, but maybe I
will some day ;-). Or well, I've seen documentation for said register,
but that does not match with the comment (but seems to indicate that 0
is a reasonable value to write there).

At this point, I can really only say that I can now easily reproduce
this with ath9k and AR5416 and zeroing the 0x41 value does make the
problem disappear. Since that code has been in use for five years, I do
not expect problems with it and we can just eventually fix the comment
if somebody actually find out what that register is supposed to control
;-).
 
-- 
Jouni Malinen                                            PGP id EFC895FA