Author: adrian
Date: Mon May 30 15:06:57 2011
New Revision: 222498
URL: http://svn.freebsd.org/changeset/base/222498
Log:
Enable setting the short-GI bit when TX'ing HT rates but only if the
hardware supports it.
Since ni->ni_htcap in hostap mode is what the remote end has advertised,
not what has been negotiated/decided, we need to check ourselves what
the current channel width is and what the hardware supports before
enabling short-GI.
It's important that short-GI isn't enabled when it isn't negotiated
and when the hardware doesn't support it (ie, short-gi for 20mhz channels
on any chip < AR9287.)
I've quickly verified this on the AR9285 in 11n mode.
Modified:
head/sys/dev/ath/if_ath_tx_ht.c
Modified: head/sys/dev/ath/if_ath_tx_ht.c
==============================================================================
--- head/sys/dev/ath/if_ath_tx_ht.c Mon May 30 14:57:00 2011
(r222497)
+++ head/sys/dev/ath/if_ath_tx_ht.c Mon May 30 15:06:57 2011
(r222498)
@@ -136,15 +136,23 @@ ath_rateseries_setup(struct ath_softc *s
*/
if (ni->ni_chw == 40)
series[i].RateFlags |= HAL_RATESERIES_2040;
-#if 0
+
/*
- * The hardware only supports short-gi in 40mhz mode -
- * if later hardware supports it in 20mhz mode, be sure
- * to add the relevant check here.
+ * Set short-GI only if the node has advertised it
+ * the channel width is suitable, and we support it.
+ * We don't currently have a "negotiated" set of bits -
+ * ni_htcap is what the remote end sends, not what this
+ * node is capable of.
*/
- if (ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40)
+ if (ni->ni_chw == 40 &&
+ ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI40 &&
+ ni->ni_htcap & IEEE80211_HTCAP_SHORTGI40)
+ series[i].RateFlags |= HAL_RATESERIES_HALFGI;
+
+ if (ni->ni_chw == 20 &&
+ ic->ic_htcaps & IEEE80211_HTCAP_SHORTGI20 &&
+ ni->ni_htcap & IEEE80211_HTCAP_SHORTGI20)
series[i].RateFlags |= HAL_RATESERIES_HALFGI;
-#endif
series[i].Rate = rt->info[rix[i]].rateCode;
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