--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -586,6 +586,7 @@ struct ath_softc {
 	struct ieee80211_hw *hw;
 	struct device *dev;
 
+	u32 chan_bw;
 	int chan_idx;
 	int chan_is_ht;
 	struct survey_info *cur_survey;
--- a/drivers/net/wireless/ath/ath9k/debug.c
+++ b/drivers/net/wireless/ath/ath9k/debug.c
@@ -1281,6 +1281,9 @@ int ath9k_init_debug(struct ath_hw *ah)
 	debugfs_create_file("eeprom", S_IRUSR, sc->debug.debugfs_phy, sc,
 			    &fops_eeprom);
 
+	debugfs_create_u32("chanbw", S_IRUSR | S_IWUSR, sc->debug.debugfs_phy,
+			   &sc->chan_bw);
+
 	sc->debug.regidx = 0;
 	return 0;
 }
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -226,6 +226,7 @@ static int ath_set_channel(struct ath_so
 	bool fastcc = true, stopped;
 	struct ieee80211_channel *channel = hw->conf.channel;
 	struct ath9k_hw_cal_data *caldata = NULL;
+	u32 oldflags;
 	int r;
 
 	if (sc->sc_flags & SC_OP_INVALID)
@@ -268,6 +269,24 @@ static int ath_set_channel(struct ath_so
 	if (!stopped || !(sc->sc_flags & SC_OP_OFFCHANNEL))
 		fastcc = false;
 
+	oldflags = hchan->channelFlags;
+	switch (sc->chan_bw) {
+	case 5:
+		hchan->channelFlags &= ~CHANNEL_HALF;
+		hchan->channelFlags |= CHANNEL_QUARTER;
+		break;
+	case 10:
+		hchan->channelFlags &= ~CHANNEL_QUARTER;
+		hchan->channelFlags |= CHANNEL_HALF;
+		break;
+	default:
+		hchan->channelFlags &= ~(CHANNEL_HALF | CHANNEL_QUARTER);
+		break;
+	}
+
+	if (oldflags != hchan->channelFlags)
+		fastcc = false;
+
 	if (!(sc->sc_flags & SC_OP_OFFCHANNEL))
 		caldata = &sc->caldata;