mac80211: Interoperability workaround for 80+80 and 160 MHz channels (23665aaf) · Commits · 戴 / test

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 <jouni@qca.qualcomm.com> Signed-off-by:

Johannes Berg <johannes.berg@intel.com>

net/mac80211/util.c

+29 −2

Original line number	Diff line number	Diff line
		@@ -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;

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