rtwn: add a default OFDM / CCK rate for self-generated frames

I noticed during testing that the MAC was generating MCS7 ACKs and
MCS7 block-ACK frames in response to MCS frames from its peer.
This is very suboptimal - it means that unless you're very close
to your peer (in this case a 2GHz AP), you'll end up failing a lot
of ACKs.

Linux faced the opposite problem in rtl8xxxu - the rate set being
programmed in here included a lot MORE rates, including MCS 0->7
and OFDM 6M->54M.  This meant that they were INTENTIONALLY telling
the hardware to transmit at higher rates, and their fix was to
mask out the higher rates so self-generated frames don't try the
high rates at all.

Now, I am not sure why I'm not seeing any OFDM or HT basic rates.
We don't mark any OFDM / HT rates as basic in net80211 (in
ieee80211_phy.c) so I'm going to need to go and do a review of the
standard to see what's up.  Additionally, the HT rate set that we
populate isn't tagging any of the HT rates as IEEE80211_RATE_BASIC,
so the code I added for now is a no-op.

So:

* Extend rtwn_get_rates() and its consumers to populate the HT rateset
  with basic rates if they're provided
* Add a default 2GHz / 5GHz mask, inspired by linux, applied over the
  basic rates provided.
* Make sure there's at least an OFDM rate (for 2G/5G) rate available if
  the peer node is HT, which avoids the MAC defaulting to MCS7 when
  generating ACK/block-ACK.
* Add register definitions for INIDATA/INIRTS, which set the default
  data rate when the driver doesn't specify the initial data / RTS/CTS
  rates in the TX descriptor.
* Leave a comment about why I've modified the mask from Linux.

Locally tested:

* RTL8192CU, STA mode
* RTL8188EU, STA mode
* RTL8192EU, STA mode
* RTL8812AU, STA mode

Differential Revision:	https://reviews.freebsd.org/D48019
Reviewed by:	bz

0 files changed, 0 insertions, 0 deletions