--- /dev/null
+--- a/drivers/net/wireless/ath/ath5k/ath5k.h
++++ b/drivers/net/wireless/ath/ath5k/ath5k.h
+@@ -1233,7 +1233,7 @@ int ath5k_eeprom_read_mac(struct ath5k_h
+ /* Protocol Control Unit Functions */
+ /* Helpers */
+ int ath5k_hw_get_frame_duration(struct ath5k_hw *ah,
+- int len, struct ieee80211_rate *rate);
++ int len, struct ieee80211_rate *rate, bool shortpre);
+ unsigned int ath5k_hw_get_default_slottime(struct ath5k_hw *ah);
+ unsigned int ath5k_hw_get_default_sifs(struct ath5k_hw *ah);
+ extern int ath5k_hw_set_opmode(struct ath5k_hw *ah, enum nl80211_iftype opmode);
+--- a/drivers/net/wireless/ath/ath5k/pcu.c
++++ b/drivers/net/wireless/ath/ath5k/pcu.c
+@@ -75,7 +75,7 @@ static const unsigned int ack_rates_high
+ * bwmodes.
+ */
+ int ath5k_hw_get_frame_duration(struct ath5k_hw *ah,
+- int len, struct ieee80211_rate *rate)
++ int len, struct ieee80211_rate *rate, bool shortpre)
+ {
+ struct ath5k_softc *sc = ah->ah_sc;
+ int sifs, preamble, plcp_bits, sym_time;
+@@ -84,9 +84,15 @@ int ath5k_hw_get_frame_duration(struct a
+
+ /* Fallback */
+ if (!ah->ah_bwmode) {
+- dur = ieee80211_generic_frame_duration(sc->hw,
+- NULL, len, rate);
+- return le16_to_cpu(dur);
++ __le16 raw_dur = ieee80211_generic_frame_duration(sc->hw,
++ NULL, len, rate);
++
++ /* subtract difference between long and short preamble */
++ dur = le16_to_cpu(raw_dur);
++ if (shortpre)
++ dur -= 96;
++
++ return dur;
+ }
+
+ bitrate = rate->bitrate;
+@@ -263,27 +269,14 @@ static inline void ath5k_hw_write_rate_d
+ * actual rate for this rate. See mac80211 tx.c
+ * ieee80211_duration() for a brief description of
+ * what rate we should choose to TX ACKs. */
+- tx_time = ath5k_hw_get_frame_duration(ah, 10, rate);
++ tx_time = ath5k_hw_get_frame_duration(ah, 10, rate, false);
+
+ ath5k_hw_reg_write(ah, tx_time, reg);
+
+ if (!(rate->flags & IEEE80211_RATE_SHORT_PREAMBLE))
+ continue;
+
+- /*
+- * We're not distinguishing short preamble here,
+- * This is true, all we'll get is a longer value here
+- * which is not necessarilly bad. We could use
+- * export ieee80211_frame_duration() but that needs to be
+- * fixed first to be properly used by mac802111 drivers:
+- *
+- * - remove erp stuff and let the routine figure ofdm
+- * erp rates
+- * - remove passing argument ieee80211_local as
+- * drivers don't have access to it
+- * - move drivers using ieee80211_generic_frame_duration()
+- * to this
+- */
++ tx_time = ath5k_hw_get_frame_duration(ah, 10, rate, true);
+ ath5k_hw_reg_write(ah, tx_time,
+ reg + (AR5K_SET_SHORT_PREAMBLE << 2));
+ }
+--- a/drivers/net/wireless/ath/ath5k/qcu.c
++++ b/drivers/net/wireless/ath/ath5k/qcu.c
+@@ -550,7 +550,7 @@ int ath5k_hw_set_ifs_intervals(struct at
+ else
+ rate = &sc->sbands[IEEE80211_BAND_2GHZ].bitrates[0];
+
+- ack_tx_time = ath5k_hw_get_frame_duration(ah, 10, rate);
++ ack_tx_time = ath5k_hw_get_frame_duration(ah, 10, rate, false);
+
+ /* ack_tx_time includes an SIFS already */
+ eifs = ack_tx_time + sifs + 2 * slot_time;
--- /dev/null
+--- a/drivers/net/wireless/ath/ath5k/ath5k.h
++++ b/drivers/net/wireless/ath/ath5k/ath5k.h
+@@ -224,8 +224,7 @@
+
+ /* SIFS */
+ #define AR5K_INIT_SIFS_TURBO 6
+-/* XXX: 8 from initvals 10 from standard */
+-#define AR5K_INIT_SIFS_DEFAULT_BG 8
++#define AR5K_INIT_SIFS_DEFAULT_BG 10
+ #define AR5K_INIT_SIFS_DEFAULT_A 16
+ #define AR5K_INIT_SIFS_HALF_RATE 32
+ #define AR5K_INIT_SIFS_QUARTER_RATE 64
+--- a/drivers/net/wireless/ath/ath5k/qcu.c
++++ b/drivers/net/wireless/ath/ath5k/qcu.c
+@@ -519,7 +519,7 @@ int ath5k_hw_set_ifs_intervals(struct at
+ return -EINVAL;
+
+ sifs = ath5k_hw_get_default_sifs(ah);
+- sifs_clock = ath5k_hw_htoclock(ah, sifs);
++ sifs_clock = ath5k_hw_htoclock(ah, sifs - 2);
+
+ /* EIFS
+ * Txtime of ack at lowest rate + SIFS + DIFS
--- /dev/null
+--- a/drivers/net/wireless/ath/ath5k/ath5k.h
++++ b/drivers/net/wireless/ath/ath5k/ath5k.h
+@@ -1057,6 +1057,7 @@ struct ath5k_hw {
+ u8 ah_coverage_class;
+ bool ah_ack_bitrate_high;
+ u8 ah_bwmode;
++ bool ah_short_slot;
+
+ /* Antenna Control */
+ u32 ah_ant_ctl[AR5K_EEPROM_N_MODES][AR5K_ANT_MAX];
+--- a/drivers/net/wireless/ath/ath5k/mac80211-ops.c
++++ b/drivers/net/wireless/ath/ath5k/mac80211-ops.c
+@@ -282,6 +282,15 @@ ath5k_bss_info_changed(struct ieee80211_
+ if (changes & BSS_CHANGED_BEACON_INT)
+ sc->bintval = bss_conf->beacon_int;
+
++ if (changes & BSS_CHANGED_ERP_SLOT) {
++ int slot_time;
++
++ ah->ah_short_slot = bss_conf->use_short_slot;
++ slot_time = ath5k_hw_get_default_slottime(ah) +
++ 3 * ah->ah_coverage_class;
++ ath5k_hw_set_ifs_intervals(ah, slot_time);
++ }
++
+ if (changes & BSS_CHANGED_ASSOC) {
+ avf->assoc = bss_conf->assoc;
+ if (bss_conf->assoc)
+--- a/drivers/net/wireless/ath/ath5k/pcu.c
++++ b/drivers/net/wireless/ath/ath5k/pcu.c
+@@ -151,9 +151,9 @@ unsigned int ath5k_hw_get_default_slotti
+ slot_time = AR5K_INIT_SLOT_TIME_QUARTER_RATE;
+ break;
+ case AR5K_BWMODE_DEFAULT:
+- slot_time = AR5K_INIT_SLOT_TIME_DEFAULT;
+ default:
+- if (channel->hw_value & CHANNEL_CCK)
++ slot_time = AR5K_INIT_SLOT_TIME_DEFAULT;
++ if ((channel->hw_value & CHANNEL_CCK) && !ah->ah_short_slot)
+ slot_time = AR5K_INIT_SLOT_TIME_B;
+ break;
+ }