Hello Developers! I am trying to change channel type/width (HT20/HT40+) on the both STA and AP side in a simple system consists of only 1 STA and the AP. AP is started using hostapd under HT20 and STA thereafter connects to it using also HT20. But when AP changes its channel type to HT40+ using ieee80211_set_channel_type() and ath9k_hw_set_channel_regs(), it will lose connection to STA. The way I do channel type change coordination is: STA sends an action frame to AP, AP sends back ACK frame and changes its channel type; STA changes its channel type on receiving the ACK. I read about this solution (http://eznemegy.blog.hu/2008/12/14/using_rt2x00_wireless_driver_with_hostapd/fullcommentlist/1) of hacking into hostapd, which didn't work... It would be great if you more experienced would love to help me with this problem! related code: /* zhe: on receiving NCW action frame */ switch (mgmt->u.action.u.ht_ncw.action) { case WLAN_HT_ACTION_NOTIFY_CHANWIDTH: printk("<1>zhe: ncw action frame received: %d\n", mgmt->u.action.u.ht_ncw.ncw_control); // zhe: change channel width, init rate table struct ieee80211_supported_band *sband; sband = rx->local->hw.wiphy->bands[status->band]; u8 ncw = mgmt->u.action.u.ht_ncw.ncw_control; enum nl80211_channel_type chantype; switch (mgmt->u.action.u.ht_ncw.ncw_control) { case WLAN_HT_NCW_CONTROL_20MHZ: printk("<1>zhe: change to 20MHZ BW\n"); rx->sta->sta.ht_cap.cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40; rx->sta->sta.ht_cap.cap |= IEEE80211_HT_CAP_SGI_20; local->hw.conf.channel_type = NL80211_CHAN_HT20; chantype = NL80211_CHAN_HT20; break; case WLAN_HT_NCW_CONTROL_OTHER: printk("<1>zhe: change to 40MHZ BW\n"); rx->sta->sta.ht_cap.cap &= ~IEEE80211_HT_CAP_SGI_20; rx->sta->sta.ht_cap.cap |= IEEE80211_HT_CAP_SUP_WIDTH_20_40; local->hw.conf.channel_type = NL80211_CHAN_HT40PLUS; chantype = NL80211_CHAN_HT40PLUS; break; } // on AP side, the implementation of RC_BW_CHANGED is exactly the same // with the dirver build-in code for STA rate update rate_control_rate_update(local, sband, rx->sta,IEEE80211_RC_BW_CHANGED); ieee80211_set_channel_type(local, sdata, chantype); int ret; // i add this function, which calls ath9k_hw_set_channel_regs() to // to config channel (e.g. CHANNEL_A_HT20, CHANNEL_A_HT40PLUS) ret = ieee80211_hw_set_channel_type(local, chantype); goto handled; Thanks in advance!! Zhe -- Zhe Wen -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
