Number of deployed 80 MHz capable VHT stations that do not support 80+80 and 160 MHz bandwidths seem to misbehave when trying to connect to an AP that advertises 80+80 or 160 MHz channel bandwidth in the VHT Operation element. To avoid such issues with deployed devices, modify the design based on recently accepted IEEE 802.11 standard changes (*).
This allows poorly implemented VHT 80 MHz stations to connect with the AP in 80 MHz mode. 80+80 and 160 MHz capable stations need to support the new workaround mechanism to allow full bandwidth to be used. However, there are more or less no impacted station with 80+80/160 capability deployed. The rebased version of this patch is based on the updated version from Johannes Berg to take the HT/VHT chandef refactoring into account. (*) Changes in https://mentor.ieee.org/802.11/dcn/15/11-15-1530-04-000m-vht160-operation-signaling-through-non-zero-ccfs1.docx were accepted during the IEEE 802.11 January 2016 meeting. Signed-off-by: Jouni Malinen <[email protected]> --- net/mac80211/util.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/net/mac80211/util.c b/net/mac80211/util.c index fb90d9c..df1eca8 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -2364,10 +2364,23 @@ u8 *ieee80211_ie_build_vht_oper(u8 *pos, struct ieee80211_sta_vht_cap *vht_cap, switch (chandef->width) { case NL80211_CHAN_WIDTH_160: - vht_oper->chan_width = IEEE80211_VHT_CHANWIDTH_160MHZ; + /* + * Convert 160 MHz channel width to new style as interop + * workaround. + */ + vht_oper->chan_width = IEEE80211_VHT_CHANWIDTH_80MHZ; + vht_oper->center_freq_seg2_idx = vht_oper->center_freq_seg1_idx; + if (chandef->chan->center_freq < chandef->center_freq1) + vht_oper->center_freq_seg1_idx -= 8; + else + vht_oper->center_freq_seg1_idx += 8; break; case NL80211_CHAN_WIDTH_80P80: - vht_oper->chan_width = IEEE80211_VHT_CHANWIDTH_80P80MHZ; + /* + * Convert 80+80 MHz channel width to new style as interop + * workaround. + */ + vht_oper->chan_width = IEEE80211_VHT_CHANWIDTH_80MHZ; break; case NL80211_CHAN_WIDTH_80: vht_oper->chan_width = IEEE80211_VHT_CHANWIDTH_80MHZ; @@ -2430,6 +2443,20 @@ bool ieee80211_chandef_vht_oper(const struct ieee80211_vht_operation *oper, case IEEE80211_VHT_CHANWIDTH_80MHZ: new.width = NL80211_CHAN_WIDTH_80; new.center_freq1 = cf1; + /* If needed, adjust based on the newer interop workaround. */ + if (oper->center_freq_seg2_idx) { + unsigned int diff; + + diff = abs(oper->center_freq_seg2_idx - + oper->center_freq_seg1_idx); + if (diff == 8) { + new.width = NL80211_CHAN_WIDTH_160; + new.center_freq1 = cf2; + } else if (diff > 8) { + new.width = NL80211_CHAN_WIDTH_80P80; + new.center_freq2 = cf2; + } + } break; case IEEE80211_VHT_CHANWIDTH_160MHZ: new.width = NL80211_CHAN_WIDTH_160; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
