Atheros, hardware access layer, collisions

Sam Leffler sam at
Fri Jul 22 00:25:58 GMT 2005

David Malone wrote:
>>I was looking for this in the ah.h and the ah_desc.h files.  Are they
>>someplace else, or maybe this is a system call?  I can't find anything
>>about the retry limit (<-- CWmin = retry?)  Thanks,
> CWmin is a setting that controls the random delay before packets
> are transmitted. Search for tqi_cwmin in the driver. The retry limit
> says how many times the MAC should retry if it gets a collision
> while trying to transmit - I think it is controled by the tqi_shretry
> and tqi_lgretry values. In the driver in 6.X you can (in principle)
> set these values at the time the transmit queues are configured.

You need to set cwmin on the tx q as David describes.  Be sure to set 
the parameters you set into the hardware; check the wme update code for 
the correct logic.  For the other thing just set the tx descriptor to do 
1 try.


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