Date: Mon, 6 Dec 2010 11:53:48 -0800
From: "Luis R. Rodriguez" <lrodriguez@atheros.com>
To: Luis Rodriguez <Luis.Rodriguez@Atheros.com>
CC: Ben Greear <greearb@candelatech.com>,
	Felix Fietkau <nbd@openwrt.org>,
	"ath9k-devel@lists.ath9k.org" <ath9k-devel@venema.h4ckr.net>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [ath9k-devel] Script to crash ath9k with DMA errors.
Message-ID: <20101206195348.GF21442@tux>
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 <20101206193600.GC21442@tux>
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On Mon, Dec 06, 2010 at 11:53:13AM -0800, Luis Rodriguez wrote:
> On Mon, Dec 06, 2010 at 11:47:47AM -0800, Ben Greear wrote:
> > On 12/06/2010 11:36 AM, Luis R. Rodriguez wrote:
> > 
> > > Can you clarify the status of this issue. It remains unclear to me from
> > > your above description how things are going. As I read it some things
> > > look OK now but you still get a warning.
> > 
> > Ok, since you asked :)
> > 
> > I worked on this over the weekend and this morning.  I had all sorts of
> > issues until I realized that I had one STA with non-configured SSID.
> > It sometimes connected to one /a AP and the other STAs attempted to connect
> > to another /n (on entirely different band) AP.  I basically got zero stations associated for any length
> > of time due to constant channel switching.  No crashes, but lots of
> > warnings about DMA failing to stop.
> > 
> > Now..I've fixed this configuration issue (and adding steps to help prevent this mis-configuration
> > again).
> > 
> > With 16 properly configured non-encrypted stations, running with wpa-supplicant
> > with netlink driver & sharing scan results,  the interfaces quickly associate.
> > 
> > However, I do continue to see DMA warnings such as these (I had picked up my
> > portable phone, and it knocked all the interfaces offline ..here
> > they are coming back up after I hung up the phone).
> > 
> > Please note that I ported Felix's 2.6.37 patch he posted this morning
> > to wireless-testing and have applied it.
> > 
> > I'm highly tempted to just make that a WARN_ON_ONCE so at least my logs
> > aren't spammed so heavily with the recv.c:531 DMA warning.
> 
> You can send this change upstream as well.

Also, feel free to limit the number of STAs you can have up
physically by setting this to a number you bless yourself.

  Luis