[ath9k-devel] DMA TX Errors

[Pannir <pannir@xsmail.com>]

Paul Farrow <ath9k <at> thefabfarrows.com> writes:

> 
> Continuation of DMA errors saga...
> 
> Way back when, I bought a 9380 Sparklan card and it worked fine.  And 
> it continues to work fine with my little duo board.  But I was getting 
> really bad speeds from it (586kbps) so thought it was because I only had 
> two of the antennas hooked up so decided to buy another 9280 card this 
> time from Sparklan as I had had good experience with the 9380 one.   So 
> last night I popped it into the motherboard and exactly the same problem 
> that I had before with the apple 9280 card I have.
> 
> Ran it up as an access point and connect to it.  Normal browsing seems 
> to be fine but as soon as I try to stream video (ie heavy usage) the DMA 
> errors start and the machine is unusable.  I am using a 3.3.8-1 x86_64 
> kernel on the Fedora FC16 distribution.
> 
> I guess the point of this post is to say I still have problems (with 
> certain cards) and was wondering if there has been any developments with 
> the DMA issues that people see and continue to see?
> 
> Irritated by it and keep thinking it will be fixed - I just cant seem 
> to let it go plus the costs are creeping up :(
> 


I have been seeing the same problem with the AR9280 on our MPC8315 based boards.
It does not happen on all our boards but the error seems to happen quicker on
some boards compared to others. I have not seen the issue on some boards. But
then again I have not tested any boards for more than 2 days. The problem
disappeared when I replaced the module with AR9382 from Unex (it is also 2x2).
The intermittent nature of the problem is making it difficult to troubleshoot on
the hardware level. Why is it happening on some boards and not others? Why is
AR9382 more forgiving than AR9280?