The regular RX path has a lot of code, but with a few
assumptions on the hardware it's possible to reduce the
amount of code significantly. Currently the assumptions
on the driver are the following:
* hardware/driver reordering buffer (if supporting aggregation)
* hardware/driver decryption & PN checking (if using encryption)
* hardware/driver did de-duplication
* hardware/driver did A-MSDU deaggregation
* AP_LINK_PS is used (in AP mode)
* no client powersave handling in mac80211 (in client mode)
of which some are actually checked per packet:
* de-duplication
* PN checking
* decryption
and additionally packets must
* not be A-MSDU (have been deaggregated by driver/device)
* be data packets
* not be fragmented
* be unicast
* have RFC 1042 header
Additionally dynamically we assume:
* no encryption or CCMP/GCMP, TKIP/WEP/other not allowed
* station must be authorized
* 4-addr format not enabled
Some data needed for the RX path is cached in a new per-station
"fast_rx" structure, so that we only need to look at this and
the packet, no other memory when processing packets on the fast
RX path.
After doing the above per-packet checks, the data path collapses
down to a pretty simple conversion function taking advantage of
the data cached in the small fast_rx struct.
This should speed up the RX processing, and will make it easier
to reason about parallelizing RX (for which statistics will need
to be per-CPU still.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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