Intermittent "failed to stop TX DMA"

[Norman Henderson]

Hi, I am getting intermittent messages (a burst e.g. 6 in a 5 min period
then nothing for an hour or more):
ath: phy0: Failed to stop TX DMA, queues = 0x002! (or 008 or 00a or 100 or
102 or...)

Initially I was running on a Dell Optiplex 390, Ubuntu 14.04.2/ hostapd
2.1/ ath9k (all stock, as distributed via Ubuntu). All fully patched
(kernel 3.16.0-36-generic). Then  I installed the latest backports stable
version of ath9k and the messages seemed to be less frequent - but didn't
go away.

The wireless card is a DLink DWA-566 (AR-9300) - pretty basic.

Can anyone tell me what I am dealing with here? Is this a problem or just
log spam? Is there a way to fix it?

Thanks, Norm
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