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[ath] don't do LDPC, STBC or short-gi for locationing frames.

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The 11n duration calculation function in net80211 and the HAL round /up/
the duration calculation for short-gi, so we can't use that.

The 11n duration calculation doesn't know about the extra symbol time
needed for STBC, nor the LDPC encoding duration, so we can't use
that.

This (along with other, local hacks) allow the locationing services to
get down to around 200nS (yes, nanoseconds) of variance when speaking
to a "good" AP.

Tested:

* AR9380, STA mode, local locationing frame hacks
This commit is contained in:
Adrian Chadd 2016-07-19 00:27:17 +00:00
parent eef722c337
commit ffa25bec32
1 changed files with 26 additions and 4 deletions
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30
sys/dev/ath/if_ath_tx_ht.c
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@ -242,6 +242,14 @@ ath_tx_rate_fill_rcflags(struct ath_softc *sc, struct ath_buf *bf)
if ((ni->ni_vap->iv_htcaps & IEEE80211_HTCAP_LDPC) &&
(ni->ni_htcap & IEEE80211_HTCAP_LDPC))
do_ldpc = 1;
/*
* The 11n duration calculation doesn't know about LDPC,
* so don't enable it for positioning.
*/
if (bf->bf_flags & ATH_BUF_TOA_PROBE)
do_ldpc = 0;
do_stbc = 0;
for (i = 0; i < ATH_RC_NUM; i++) {
@ -279,29 +287,43 @@ ath_tx_rate_fill_rcflags(struct ath_softc *sc, struct ath_buf *bf)
if (ni->ni_chw == 40)
rc[i].flags |= ATH_RC_CW40_FLAG;
/*
* NOTE: Don't do short-gi for positioning frames.
*
* For now, the ath_hal and net80211 HT duration
* calculation rounds up the 11n data txtime
* to the nearest multiple of 3.6 microseconds
* and doesn't return the fractional part, so
* we are always "out" by some amount.
*/
if (ni->ni_chw == 40 &&
ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40 &&
ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40 &&
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40)
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI40 &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_SGI_FLAG;
}
if (ni->ni_chw == 20 &&
ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20 &&
ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20 &&
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20)
vap->iv_flags_ht & IEEE80211_FHT_SHORTGI20 &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_SGI_FLAG;
}
/*
* If we have STBC TX enabled and the receiver
* can receive (at least) 1 stream STBC, AND it's
* MCS 0-7, AND we have at least two chains enabled,
* enable STBC.
* and we're not doing positioning, enable STBC.
*/
if (ic->ic_htcaps & IEEE80211_HTCAP_TXSTBC &&
ni->ni_vap->iv_flags_ht & IEEE80211_FHT_STBC_TX &&
ni->ni_htcap & IEEE80211_HTCAP_RXSTBC_1STREAM &&
(sc->sc_cur_txchainmask > 1) &&
HT_RC_2_STREAMS(rate) == 1) {
(HT_RC_2_STREAMS(rate) == 1) &&
(bf->bf_flags & ATH_BUF_TOA_PROBE) == 0) {
rc[i].flags |= ATH_RC_STBC_FLAG;
do_stbc = 1;
}