VHT: Add an interoperability workaround for 80+80 and 160 MHz channels

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 newly proposed 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.

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

diff --git a/src/ap/ieee802_11_vht.c b/src/ap/ieee802_11_vht.c
index 3236016..e923094 100644
--- a/src/ap/ieee802_11_vht.c
+++ b/src/ap/ieee802_11_vht.c
@@ -82,6 +82,27 @@ u8 * hostapd_eid_vht_operation(struct hostapd_data *hapd, u8 *eid)
 
 	oper->vht_op_info_chwidth = hapd->iconf->vht_oper_chwidth;
 
+	if (hapd->iconf->vht_oper_chwidth == 2) {
+		/*
+		 * Convert 160 MHz channel width to new style as interop
+		 * workaround.
+		 */
+		oper->vht_op_info_chwidth = 1;
+		oper->vht_op_info_chan_center_freq_seg1_idx =
+			oper->vht_op_info_chan_center_freq_seg0_idx;
+		if (hapd->iconf->channel <
+		    hapd->iconf->vht_oper_centr_freq_seg0_idx)
+				oper->vht_op_info_chan_center_freq_seg0_idx -= 8;
+			else
+				oper->vht_op_info_chan_center_freq_seg0_idx += 8;
+	} else if (hapd->iconf->vht_oper_chwidth == 3) {
+		/*
+		 * Convert 80+80 MHz channel width to new style as interop
+		 * workaround.
+		 */
+		oper->vht_op_info_chwidth = 1;
+	}
+
 	/* VHT Basic MCS set comes from hw */
 	/* Hard code 1 stream, MCS0-7 is a min Basic VHT MCS rates */
 	oper->vht_basic_mcs_set = host_to_le16(0xfffc);
