[rt2x00-users] rt2800: missing parts for 11n support

Ivo Van Doorn ivdoorn at gmail.com
Fri May 7 21:37:25 AEST 2010


> using 11n MCS rates works already fine with the rt2800 devices when hardcoded
> in the tx descriptor ;) as far as I could see also reception of MCS rates works
> fine as long as HT20 is used.

Even for receiving?

> I also tried minstrel_ht but that triggered a lot of warnings because of
> the missing ampdu_action callback. Just returning an error in the callback
> allows the rc algorithm to choose MCS rates but will reject all ba sessions.
> But since minstrel_ht is not upstream yet it doesn't make sense to send
> a patch for that.
> Nevertheless, in order to get "real" 11n support we would have to implement
> the ampdu_action callback to set up the ba sessions in the device.
> Did I miss anything here or is it really only this one bit missing to get
> 11n support?

Aggregation support is missing, both on the receiving as sending side.
That is one of the most important things which must be implemented for
full 11n support. I believe the receiving side must be implemented to fix
some loss of RX frames. The hardware seems to receive multiple frames
in one block, as-if it was aggregated for some regular frames as well. This
was at least reported some months ago by somebody.


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