Re: iwn(4) hangs after r257133

On Sun, Nov 10, 2013 at 02:01:12PM -0800, Adrian Chadd wrote:
> Yes. So one of the.. unfortunately broken things in iwn is the ampdu tx
> code doesn't do retransmits. So if amrr picks a rate that fails to transmit
> everything, the driver doesn't retransmit them. It frees them.
> 
> Now when amrr is enabled the hardware will retry at lower rates until
> something succeeds. But it still doesn't retransmit things. I believe it
> should be.
> 
> So yes its more broken with Mrr disabled. But enabling mrr doesn't fix it.
> It just makes it less broken. Someone needs to implement ampdu retransmit.
> 
> The latest iwn code in head at least tells the rate selection code that a
> total ampdu tx failure occured. This BTW is one of the hangs I fixed - if
> you hit a point where you never successfully transmitted an ampdu at a rate
> the rate would never be decreased.
> 
> Now to be clear. I won't be in implementing ampdu retransmit. I'll maybe
> fix last multi rate retry once the new hardware support is in. I would
> really appreciate help here with these. Everyone with iwn hardware will
> appreciate it :)

In the mean time, wouldn't it make sense to disable ampdu tx in iwn
then? Or to disallow the combination Mrr + ampdu?

Stefan