[ath9k-devel] Recurring “Failed to stop TX DMA” error

[Robbie Smith <zoqaeski@gmail.com>]

Hello list

I?ve been having issues with the stability of my network connections 
using the ath9k driver. Connections will drop for no apparent reason, 
packets seem to get lost in transit, and streaming seems to hang. 
Checking my logs I get a whole lot of messages along the lines of the 
following:

> Jun 19 00:03:08 gallifrey kernel: ath: phy0: Failed to stop TX DMA, queues=0x004!
> Jun 19 00:03:39 gallifrey kernel: cfg80211: Calling CRDA to update world regulatory domain
> Jun 19 00:03:39 gallifrey kernel: cfg80211: World regulatory domain updated:
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211: Calling CRDA for country: AU
> Jun 19 00:03:39 gallifrey kernel: cfg80211: Regulatory domain changed to country: AU
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2300 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2300 mBm)
> Jun 19 00:03:39 gallifrey kernel: cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm)
> Jun 19 00:03:40 gallifrey kernel: wlan0: authenticate with c8:be:19:58:16:58
> Jun 19 00:03:40 gallifrey kernel: wlan0: send auth to c8:be:19:58:16:58 (try 1/3)
> Jun 19 00:03:40 gallifrey kernel: wlan0: authenticated
> Jun 19 00:03:40 gallifrey kernel: wlan0: associate with c8:be:19:58:16:58 (try 1/3)
> Jun 19 00:03:40 gallifrey kernel: wlan0: RX AssocResp from c8:be:19:58:16:58 (capab=0x411 status=0 aid=1)
> Jun 19 00:03:40 gallifrey kernel: wlan0: associated
> Jun 19 00:03:40 gallifrey kernel: cfg80211: Calling CRDA for country: AU
> Jun 19 00:03:40 gallifrey kernel: ath: regdomain 0x8024 updated by CountryIE
> Jun 19 00:03:40 gallifrey kernel: ath: EEPROM regdomain: 0x8024
> Jun 19 00:03:40 gallifrey kernel: ath: EEPROM indicates we should expect a country code
> Jun 19 00:03:40 gallifrey kernel: ath: doing EEPROM country->regdmn map search
> Jun 19 00:03:40 gallifrey kernel: ath: country maps to regdmn code: 0x21
> Jun 19 00:03:40 gallifrey kernel: ath: Country alpha2 being used: AU
> Jun 19 00:03:40 gallifrey kernel: ath: Regpair used: 0x21
> Jun 19 00:03:40 gallifrey kernel: cfg80211: Regulatory domain changed to country: AU
> Jun 19 00:03:40 gallifrey kernel: cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
> Jun 19 00:03:40 gallifrey kernel: cfg80211:   (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm)
> Jun 19 00:03:40 gallifrey kernel: cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2300 mBm)
> Jun 19 00:03:40 gallifrey kernel: cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2300 mBm)
> Jun 19 00:03:40 gallifrey kernel: cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm)
> ?
> Jun 19 00:13:24 gallifrey kernel: ath: phy0: Failed to stop TX DMA, queues=0x004!
> Jun 19 00:13:39 gallifrey kernel: ath: phy0: Failed to stop TX DMA, queues=0x004!
> Jun 19 00:13:42 gallifrey kernel: ath: phy0: Failed to stop TX DMA, queues=0x004!
> Jun 19 00:13:43 gallifrey kernel: ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x00006100
> Jun 19 00:13:43 gallifrey kernel: ath: phy0: Could not stop RX, we could be confusing the DMA engine when we start RX up

If I read that output correctly, I?m getting the infamous TX DMA bug, 
and for some reason the computer repeatedly attempts to reconnect to the 
network. This only occurs on WPA protected networks, mainly on the one 
in my residence, which I do not have administrative rights to.

I?ve got a Atheros AR9485 network card, and I?m currently running the 
3.9.6 kernel (x86_64) on Arch Linux, though this issue occurs on every 
3.x kernel I?ve tested. I?ve tried running the compat-drivers on older 
kernels, but I can?t compile it on the current release, nor have I had 
much success with the backports driver (are they the same release with 
different names?).

Is there any more information I could provide that might help pinpoint 
what is happening?