On 02/26/15 06:55, Linus Torvalds wrote:

Because it looks like the brcmsmac driver has*exactly*  the same
behavior with this AP (in an Apple Macbook air). I assume brcmsmac
uses the net/80211/tx.c logic too.

That makes sense as brcmsmac is a mac80211 driver that uses the 
minstrel-ht rate control algorithm. iwlwifi is also a mac80211 driver 
but it uses a different rate control algorithm so if you have that lying 
around it would be interesting to test that (if you did not already do 
that).

Regards,
Arend