[ath9k-devel] txop bursts issues

[Claudio Pisa <claudio.pisa@uniroma2.it>]

Hello.
Some updates follow inline.

On 05/24/2012 04:14 PM, Claudio Pisa wrote:
> I am working on a research project that uses the txop mechanism to
> distinguish, on a 802.11b/g STA, between packet losses caused by
> collisions and by noise.
> 
> I found some issues that are not clear to me on both mac80211 and ath9k,
> but hopefully you can help.
> 
> The first one is the motivation behind commit
> 133a3ff2c934223a8143bfa52401bba962a97165, "cfg80211: allow setting TXQ
> parameters only in AP mode". Is this just a temporary fix?

It looks like this is in the standard, as section "9.9.1.2 EDCA TXOPs"
says that "The TXOP limit duration values are advertised by the AP". Sorry.


> To get around this, and activate the txop functionality on a STA, I am
> just hardcoding the burstTime (qi.tqi_burstTime = 102;)

I rolled back these changes and configured the AP to advertise the
txoplimit duration values.

However, from our tests, the TXOP mechanism is still not working for the
setup ath9k+AR5008, while it works for other setups (madwifi+AR242x).
Is this a driver or just a hardware issue?


> Then: is the duration field set by the hardware? We are using a D-Link
> AR5008 NIC. It seems like the driver is always setting the duration to 0
> due to (what I think is) a bug in net/mac80211/tx.c 

I have submitted a (1 byte) patch to fix this:
http://marc.info/?l=linux-wireless&m=133820812304929&w=2

thanks and regards,
Claudio