I'll clear how it's supposed to work with Bernhard and then look
at enabling this in the correct situations.
But this -does- enable HT RTS protection (using the appropriate legacy
rates) if this bit of code is enabled.
* Turn ath_tx_calc_ctsduration() into a function that
returns the ctsduration, or -1 for HT rates;
* add a printf() to ath_tx_calc_ctsduration() which will be
very loud if somehow that function is called with an MCS
rate;
* Add ath_tx_get_rtscts_rate() which returns the RTS/CTS
rate to use for the given data rate, incl. the short
preamble flag;
* Only call ath_tx_calc_ctsduration() for non-11n chipsets;
11n chipsets don't require the rtscts duration to be
calculated.
correctly:
* pass in whether to allow the hardware to override the duration field
in the main data frame (durupdate_en) - PS_POLL frames in particular
don't have the duration bit overriden;
* there's no rts/cts duration here; that's done elsehwere
This isn't strictly required to TX (at least non-agg and non-HT40,
non-short-GI) frames; but as it needs to be done anyway, just get
it done.
Linux ath9k uses the rate scenario style path for -all- packets,
legacy or otherwise. This code does much the same.
Beacon TX still uses the legacy, non-rate-scenario TX descriptor
setup. Ath9k also does this.
This 11n rate scenario path is only called for chips in the AR5416
HAL; legacy chips use the previous interface for TX'ing.
function; which will be later used by the TX path to determine
whether to use the extended features or not.
* Break out the descriptor chaining logic into a separate function;
again so it can be switched out later on for the 11n version when
needed.
* Refactor out the encryption-swizzling code that's common in the
raw and normal TX path.
There's two reasons for this:
* the raw and non-raw TX path shares a lot of duplicate code which should be
refactored;
* the 11n-ready chip TX path needs a little reworking.
