ath9k: DMA failed to stop in 10 ms

ath9k: DMA failed to stop in 10 ms

[Johannes Stezenbach]

Hi,

I have a Samsung N130 netbook which has

  phy0: Atheros AR9285 MAC/BB Rev:2 AR5133 RF Rev:e0: mem=0xf80e0000, irq=16

and I run Debain unstable with a linux-2.6.32-rc6-166-g799dd75 kernel.


When running kismet I get a lot of

[ 2030.531809] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2030.731944] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2030.968118] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2031.169580] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2031.397604] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2031.653803] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2031.883503] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2032.092719] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2032.332719] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
[ 2032.539756] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020

This is 100% reproducable.  However it seems kismet is still working
(but probably missing some frames due to the issue).


Connecting to and AP via WPA2 works (but I didn't test much yet), but
when I terminate wpa_supplicant I also get one of the "DMA failed to stop"
messages (same AR_CR and AR_DIAG_SW).


Is it safe to assume that the message is caused by an invalid
RX DMA descriptor?  Or hat else could cause DMA to fail to complete?


Thanks
Johannes

Re: ath9k: DMA failed to stop in 10 ms

[Johannes Stezenbach]

On Thu, Nov 12, 2009 at 04:26:00PM +0100, Johannes Stezenbach wrote:
> 
> When running kismet I get a lot of
> 
> [ 2030.531809] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020

Update: It seems that this is only happening when kismet is hopping
channels.  So it looks like an unclean shutdown of the receive
process and not a real problem -- except that the log flooding is
pretty annoying.


Johannes

Re: ath9k: DMA failed to stop in 10 ms

[Luis R. Rodriguez]

On Thu, Nov 12, 2009 at 10:10 AM, Johannes Stezenbach <js@sig21.net> wrote:
> On Thu, Nov 12, 2009 at 04:26:00PM +0100, Johannes Stezenbach wrote:
>>
>> When running kismet I get a lot of
>>
>> [ 2030.531809] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
>
> Update: It seems that this is only happening when kismet is hopping
> channels.  So it looks like an unclean shutdown of the receive
> process and not a real problem -- except that the log flooding is
> pretty annoying.

Can you try disabling powersave before using monitor mode?

sudo iwconfig wlan0 power off

  Luis

Re: ath9k: DMA failed to stop in 10 ms

[Luis R. Rodriguez]

On Thu, Nov 12, 2009 at 10:13 AM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
> On Thu, Nov 12, 2009 at 10:10 AM, Johannes Stezenbach <js@sig21.net> wrote:
>> On Thu, Nov 12, 2009 at 04:26:00PM +0100, Johannes Stezenbach wrote:
>>>
>>> When running kismet I get a lot of
>>>
>>> [ 2030.531809] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
>>
>> Update: It seems that this is only happening when kismet is hopping
>> channels.  So it looks like an unclean shutdown of the receive
>> process and not a real problem -- except that the log flooding is
>> pretty annoying.
>
> Can you try disabling powersave before using monitor mode?
>
> sudo iwconfig wlan0 power off

That is, we shoudn't be sleeping during monitor mode. Curious if
somehow we are getting to that state.

  Luis

Re: ath9k: DMA failed to stop in 10 ms

[Johannes Stezenbach]

On Thu, Nov 12, 2009 at 10:14:06AM -0800, Luis R. Rodriguez wrote:
> On Thu, Nov 12, 2009 at 10:13 AM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
> > On Thu, Nov 12, 2009 at 10:10 AM, Johannes Stezenbach <js@sig21.net> wrote:
> >> On Thu, Nov 12, 2009 at 04:26:00PM +0100, Johannes Stezenbach wrote:
> >>>
> >>> When running kismet I get a lot of
> >>>
> >>> [ 2030.531809] ath9k: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x00000020
> >>
> >> Update: It seems that this is only happening when kismet is hopping
> >> channels.  So it looks like an unclean shutdown of the receive
> >> process and not a real problem -- except that the log flooding is
> >> pretty annoying.
> >
> > Can you try disabling powersave before using monitor mode?
> >
> > sudo iwconfig wlan0 power off
> 
> That is, we shoudn't be sleeping during monitor mode. Curious if
> somehow we are getting to that state.

"iwconfig wlan0 power off" doesn't make a difference.


Johannes