[][MAC80211][WiFi6][hostapd][Backport hostapd ACS patches and some ACS fixes]
[Description]
Fix ACS issues in WiFi6 Codebase.
Backport the upstream hostapd commits about ACS.
ACS: Allow selecting a better channel when using 40/80/160 MHz
ACS: introduce acs_adjust_secondary
ACS: Introduce acs_get_bw_center_chan()
ACS: Extract bw40/80/160 freqs out of acs_usable_bwXXX_chan()
Fix Issue#1. Add 2.4G HT40- support
1. Add 2.4G HT40- support
2. Fix issue: selected best channel is out of channels
Fix Issue#2. Fix chan_switch to usable DFS channel fail due to ACS
[Release-log]
N/A
Change-Id: I56ff786744da83791f0134e0a1185abdf9c49bfb
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8237859
diff --git a/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0001-ACS-Extract-bw40-80-160-freqs-out-of-acs_usable_bwXX.patch b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0001-ACS-Extract-bw40-80-160-freqs-out-of-acs_usable_bwXX.patch
new file mode 100644
index 0000000..be0bc74
--- /dev/null
+++ b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0001-ACS-Extract-bw40-80-160-freqs-out-of-acs_usable_bwXX.patch
@@ -0,0 +1,172 @@
+From 8df5520f49796e4e292de6895aa0bc518978b377 Mon Sep 17 00:00:00 2001
+From: Nicolas Escande <nico.escande@gmail.com>
+Date: Wed, 27 Apr 2022 15:36:59 +0200
+Subject: [PATCH 01/50] ACS: Extract bw40/80/160 freqs out of
+ acs_usable_bwXXX_chan()
+
+This extracts the 3 lists of allowed channels for 40/80/160 MHz
+bandwidth out of their respective functions. It also adds for each
+segment the frequency of the segment's last channel and the index of the
+segment's "center" channel.
+
+This is preparative work to allow selecting a channel which is not the
+first of its segment for 40/80/160 MHz. In addition, this adds the 5 GHz
+160 MHz channel defined for 5735-5895 MHz (channels 149-177).
+
+Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
+---
+ src/ap/acs.c | 107 ++++++++++++++++++++++++++++++---------------------
+ 1 file changed, 63 insertions(+), 44 deletions(-)
+
+diff --git a/src/ap/acs.c b/src/ap/acs.c
+index 4a0a4c7..60c90e9 100644
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -241,6 +241,57 @@
+ * [1] http://en.wikipedia.org/wiki/Near_and_far_field
+ */
+
++enum bw_type {
++ ACS_BW40,
++ ACS_BW80,
++ ACS_BW160,
++};
++
++struct bw_item {
++ int first;
++ int last;
++ int center_chan;
++};
++
++static const struct bw_item bw_40[] = {
++ { 5180, 5200, 38 }, { 5220, 5240, 46 }, { 5260, 5280, 54 },
++ { 5300, 5320, 62 }, { 5500, 5520, 102 }, { 5540, 5560, 110 },
++ { 5580, 5600, 110 }, { 5620, 5640, 126}, { 5660, 5680, 134 },
++ { 5700, 5720, 142 }, { 5745, 5765, 151 }, { 5785, 5805, 159 },
++ { 5825, 5845, 167 }, { 5865, 5885, 175 },
++ { 5955, 5975, 3 }, { 5995, 6015, 11 }, { 6035, 6055, 19 },
++ { 6075, 6095, 27 }, { 6115, 6135, 35 }, { 6155, 6175, 43 },
++ { 6195, 6215, 51 }, { 6235, 6255, 59 }, { 6275, 6295, 67 },
++ { 6315, 6335, 75 }, { 6355, 6375, 83 }, { 6395, 6415, 91 },
++ { 6435, 6455, 99 }, { 6475, 6495, 107 }, { 6515, 6535, 115 },
++ { 6555, 6575, 123 }, { 6595, 6615, 131 }, { 6635, 6655, 139 },
++ { 6675, 6695, 147 }, { 6715, 6735, 155 }, { 6755, 6775, 163 },
++ { 6795, 6815, 171 }, { 6835, 6855, 179 }, { 6875, 6895, 187 },
++ { 6915, 6935, 195 }, { 6955, 6975, 203 }, { 6995, 7015, 211 },
++ { 7035, 7055, 219 }, { 7075, 7095, 227}, { -1, -1, -1 }
++};
++static const struct bw_item bw_80[] = {
++ { 5180, 5240, 42 }, { 5260, 5320, 58 }, { 5500, 5560, 106 },
++ { 5580, 5640, 122 }, { 5660, 5720, 138 }, { 5745, 5805, 155 },
++ { 5825, 5885, 171},
++ { 5955, 6015, 7 }, { 6035, 6095, 23 }, { 6115, 6175, 39 },
++ { 6195, 6255, 55 }, { 6275, 6335, 71 }, { 6355, 6415, 87 },
++ { 6435, 6495, 103 }, { 6515, 6575, 119 }, { 6595, 6655, 135 },
++ { 6675, 6735, 151 }, { 6755, 6815, 167 }, { 6835, 6895, 183 },
++ { 6915, 6975, 199 }, { 6995, 7055, 215 }, { -1, -1, -1 }
++};
++static const struct bw_item bw_160[] = {
++ { 5180, 5320, 50 }, { 5500, 5640, 114 }, { 5745, 5885, 163 },
++ { 5955, 6095, 15 }, { 6115, 6255, 47 }, { 6275, 6415, 79 },
++ { 6435, 6575, 111 }, { 6595, 6735, 143 },
++ { 6755, 6895, 175 }, { 6915, 7055, 207 }, { -1, -1, -1 }
++};
++static const struct bw_item *bw_desc[] = {
++ [ACS_BW40] = bw_40,
++ [ACS_BW80] = bw_80,
++ [ACS_BW160] = bw_160,
++};
++
+
+ static int acs_request_scan(struct hostapd_iface *iface);
+ static int acs_survey_is_sufficient(struct freq_survey *survey);
+@@ -370,50 +421,18 @@ acs_survey_chan_interference_factor(struct hostapd_iface *iface,
+ }
+
+
+-static int acs_usable_bw40_chan(const struct hostapd_channel_data *chan)
++static bool acs_usable_bw_chan(const struct hostapd_channel_data *chan,
++ enum bw_type bw)
+ {
+- const int allowed[] = { 5180, 5220, 5260, 5300, 5500, 5540, 5580, 5620,
+- 5660, 5745, 5785, 4920, 4960, 5955, 5995, 6035,
+- 6075, 6115, 6155, 6195, 6235, 6275, 6315, 6355,
+- 6395, 6435, 6475, 6515, 6555, 6595, 6635, 6675,
+- 6715, 6755, 6795, 6835, 6875, 6915, 6955, 6995,
+- 7035, 7075 };
+- unsigned int i;
+-
+- for (i = 0; i < ARRAY_SIZE(allowed); i++)
+- if (chan->freq == allowed[i])
+- return 1;
+-
+- return 0;
+-}
+-
+-
+-static int acs_usable_bw80_chan(const struct hostapd_channel_data *chan)
+-{
+- const int allowed[] = { 5180, 5260, 5500, 5580, 5660, 5745, 5955, 6035,
+- 6115, 6195, 6275, 6355, 6435, 6515, 6595, 6675,
+- 6755, 6835, 6915, 6995 };
+- unsigned int i;
+-
+- for (i = 0; i < ARRAY_SIZE(allowed); i++)
+- if (chan->freq == allowed[i])
+- return 1;
+-
+- return 0;
+-}
+-
+-
+-static int acs_usable_bw160_chan(const struct hostapd_channel_data *chan)
+-{
+- const int allowed[] = { 5180, 5500, 5955, 6115, 6275, 6435, 6595, 6755,
+- 6915 };
+- unsigned int i;
++ unsigned int i = 0;
+
+- for (i = 0; i < ARRAY_SIZE(allowed); i++)
+- if (chan->freq == allowed[i])
+- return 1;
++ while (bw_desc[bw][i].first != -1) {
++ if (chan->freq == bw_desc[bw][i].first)
++ return true;
++ i++;
++ }
+
+- return 0;
++ return false;
+ }
+
+
+@@ -705,7 +724,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ ((iface->conf->ieee80211n &&
+ iface->conf->secondary_channel) ||
+ is_6ghz_freq(chan->freq)) &&
+- !acs_usable_bw40_chan(chan)) {
++ !acs_usable_bw_chan(chan, ACS_BW40)) {
+ wpa_printf(MSG_DEBUG,
+ "ACS: Channel %d: not allowed as primary channel for 40 MHz bandwidth",
+ chan->chan);
+@@ -716,7 +735,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ (iface->conf->ieee80211ac || iface->conf->ieee80211ax)) {
+ if (hostapd_get_oper_chwidth(iface->conf) ==
+ CONF_OPER_CHWIDTH_80MHZ &&
+- !acs_usable_bw80_chan(chan)) {
++ !acs_usable_bw_chan(chan, ACS_BW80)) {
+ wpa_printf(MSG_DEBUG,
+ "ACS: Channel %d: not allowed as primary channel for 80 MHz bandwidth",
+ chan->chan);
+@@ -725,7 +744,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+
+ if (hostapd_get_oper_chwidth(iface->conf) ==
+ CONF_OPER_CHWIDTH_160MHZ &&
+- !acs_usable_bw160_chan(chan)) {
++ !acs_usable_bw_chan(chan, ACS_BW160)) {
+ wpa_printf(MSG_DEBUG,
+ "ACS: Channel %d: not allowed as primary channel for 160 MHz bandwidth",
+ chan->chan);
+--
+2.18.0
+
diff --git a/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0002-ACS-Introduce-acs_get_bw_center_chan.patch b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0002-ACS-Introduce-acs_get_bw_center_chan.patch
new file mode 100644
index 0000000..15e8c98
--- /dev/null
+++ b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0002-ACS-Introduce-acs_get_bw_center_chan.patch
@@ -0,0 +1,87 @@
+From 3e2fa0f4ab02538c66e61058749272565d94d111 Mon Sep 17 00:00:00 2001
+From: Nicolas Escande <nico.escande@gmail.com>
+Date: Wed, 27 Apr 2022 15:37:00 +0200
+Subject: [PATCH 02/50] ACS: Introduce acs_get_bw_center_chan()
+
+When using 40/80/160 MHz bandwidth, instead of computing the index of
+the segment center freq based on the selected channel, lets look it up
+in the bw_desc[] table.
+
+This is preparative work to allow selecting a primary channel which is
+not the first of the segment.
+
+Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
+---
+ src/ap/acs.c | 33 +++++++++++++++++++++++++++------
+ 1 file changed, 27 insertions(+), 6 deletions(-)
+
+diff --git a/src/ap/acs.c b/src/ap/acs.c
+index 60c90e9..511200d 100644
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -436,6 +436,21 @@ static bool acs_usable_bw_chan(const struct hostapd_channel_data *chan,
+ }
+
+
++static int acs_get_bw_center_chan(int freq, enum bw_type bw)
++{
++ unsigned int i = 0;
++
++ while (bw_desc[bw][i].first != -1) {
++ if (freq >= bw_desc[bw][i].first &&
++ freq <= bw_desc[bw][i].last)
++ return bw_desc[bw][i].center_chan;
++ i++;
++ }
++
++ return 0;
++}
++
++
+ static int acs_survey_is_sufficient(struct freq_survey *survey)
+ {
+ if (!(survey->filled & SURVEY_HAS_NF)) {
+@@ -936,19 +951,26 @@ bw_selected:
+
+ static void acs_adjust_center_freq(struct hostapd_iface *iface)
+ {
+- int offset;
++ int center;
+
+ wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
+
+ switch (hostapd_get_oper_chwidth(iface->conf)) {
+ case CONF_OPER_CHWIDTH_USE_HT:
+- offset = 2 * iface->conf->secondary_channel;
++ if (iface->conf->secondary_channel &&
++ iface->freq >= 2400 && iface->freq < 2500)
++ center = iface->conf->channel +
++ 2 * iface->conf->secondary_channel;
++ else if (iface->conf->secondary_channel)
++ center = acs_get_bw_center_chan(iface->freq, ACS_BW40);
++ else
++ center = iface->conf->channel;
+ break;
+ case CONF_OPER_CHWIDTH_80MHZ:
+- offset = 6;
++ center = acs_get_bw_center_chan(iface->freq, ACS_BW80);
+ break;
+ case CONF_OPER_CHWIDTH_160MHZ:
+- offset = 14;
++ center = acs_get_bw_center_chan(iface->freq, ACS_BW160);
+ break;
+ default:
+ /* TODO: How can this be calculated? Adjust
+@@ -958,8 +980,7 @@ static void acs_adjust_center_freq(struct hostapd_iface *iface)
+ return;
+ }
+
+- hostapd_set_oper_centr_freq_seg0_idx(iface->conf,
+- iface->conf->channel + offset);
++ hostapd_set_oper_centr_freq_seg0_idx(iface->conf, center);
+ }
+
+
+--
+2.18.0
+
diff --git a/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0003-ACS-introduce-acs_adjust_secondary.patch b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0003-ACS-introduce-acs_adjust_secondary.patch
new file mode 100644
index 0000000..b4ac1f0
--- /dev/null
+++ b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0003-ACS-introduce-acs_adjust_secondary.patch
@@ -0,0 +1,92 @@
+From 03dd213b918218fec270e781d284ec394fb63ef1 Mon Sep 17 00:00:00 2001
+From: Nicolas Escande <nico.escande@gmail.com>
+Date: Wed, 27 Apr 2022 15:37:01 +0200
+Subject: [PATCH 03/50] ACS: introduce acs_adjust_secondary
+
+When using 40/80/160 MHz bandwidth on the 5 GHz or 6 GHz band, enforce
+the secondary channel to be the other channel of the corresponding 40
+MHz segment.
+
+Even if this is useless for now, this is preparatory work to allow ACS
+to select a primary channel which is not the first of its segment.
+
+Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
+---
+ src/ap/acs.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
+ 1 file changed, 45 insertions(+), 1 deletion(-)
+
+diff --git a/src/ap/acs.c b/src/ap/acs.c
+index 511200d..78d1feb 100644
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -634,6 +634,26 @@ acs_find_chan_mode(struct hostapd_hw_modes *mode, int freq)
+ }
+
+
++static enum hostapd_hw_mode
++acs_find_mode(struct hostapd_iface *iface, int freq)
++{
++ int i;
++ struct hostapd_hw_modes *mode;
++ struct hostapd_channel_data *chan;
++
++ for (i = 0; i < iface->num_hw_features; i++) {
++ mode = &iface->hw_features[i];
++ if (!hostapd_hw_skip_mode(iface, mode)) {
++ chan = acs_find_chan_mode(mode, freq);
++ if (chan)
++ return mode->mode;
++ }
++ }
++
++ return HOSTAPD_MODE_IEEE80211ANY;
++}
++
++
+ static struct hostapd_channel_data *
+ acs_find_chan(struct hostapd_iface *iface, int freq)
+ {
+@@ -949,6 +969,28 @@ bw_selected:
+ }
+
+
++static void acs_adjust_secondary(struct hostapd_iface *iface)
++{
++ unsigned int i;
++
++ /* When working with bandwidth over 20 MHz on the 5 GHz or 6 GHz band,
++ * ACS can return a secondary channel which is not the first channel of
++ * the segment and we need to adjust. */
++ if (!iface->conf->secondary_channel ||
++ acs_find_mode(iface, iface->freq) != HOSTAPD_MODE_IEEE80211A)
++ return;
++
++ wpa_printf(MSG_DEBUG, "ACS: Adjusting HT/VHT/HE secondary frequency");
++
++ for (i = 0; bw_desc[ACS_BW40][i].first != -1; i++) {
++ if (iface->freq == bw_desc[ACS_BW40][i].first)
++ iface->conf->secondary_channel = 1;
++ else if (iface->freq == bw_desc[ACS_BW40][i].last)
++ iface->conf->secondary_channel = -1;
++ }
++}
++
++
+ static void acs_adjust_center_freq(struct hostapd_iface *iface)
+ {
+ int center;
+@@ -1036,8 +1078,10 @@ static void acs_study(struct hostapd_iface *iface)
+ iface->conf->channel = ideal_chan->chan;
+ iface->freq = ideal_chan->freq;
+
+- if (iface->conf->ieee80211ac || iface->conf->ieee80211ax)
++ if (iface->conf->ieee80211ac || iface->conf->ieee80211ax) {
++ acs_adjust_secondary(iface);
+ acs_adjust_center_freq(iface);
++ }
+
+ err = 0;
+ fail:
+--
+2.18.0
+
diff --git a/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0004-ACS-Allow-selecting-a-better-channel-when-using-40-8.patch b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0004-ACS-Allow-selecting-a-better-channel-when-using-40-8.patch
new file mode 100644
index 0000000..8da5856
--- /dev/null
+++ b/autobuild_mac80211_release/package/network/services/hostapd/patches/bp-0004-ACS-Allow-selecting-a-better-channel-when-using-40-8.patch
@@ -0,0 +1,78 @@
+From a615aa302064919791f3912a5cf1a908390414df Mon Sep 17 00:00:00 2001
+From: Nicolas Escande <nico.escande@gmail.com>
+Date: Wed, 27 Apr 2022 15:37:02 +0200
+Subject: [PATCH 04/50] ACS: Allow selecting a better channel when using
+ 40/80/160 MHz
+
+When considering a channel for a bandwidth of 40/80/160 MHZ on the 5 GHz
+or 6 GHz band, allow selecting one of the other channels in the segment
+instead of the first one. This is done only if the other channel's
+interference_factor is lower than the first one's.
+
+Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
+---
+ src/ap/acs.c | 25 +++++++++++++++++++++++--
+ 1 file changed, 23 insertions(+), 2 deletions(-)
+
+diff --git a/src/ap/acs.c b/src/ap/acs.c
+index 78d1feb..130e135 100644
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -712,7 +712,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ struct hostapd_channel_data **ideal_chan,
+ long double *ideal_factor)
+ {
+- struct hostapd_channel_data *chan, *adj_chan = NULL;
++ struct hostapd_channel_data *chan, *adj_chan = NULL, *best;
+ long double factor;
+ int i, j;
+ unsigned int k;
+@@ -720,8 +720,9 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ for (i = 0; i < mode->num_channels; i++) {
+ double total_weight;
+ struct acs_bias *bias, tmp_bias;
++ bool update_best = true;
+
+- chan = &mode->channels[i];
++ best = chan = &mode->channels[i];
+
+ /* Since in the current ACS implementation the first channel is
+ * always a primary channel, skip channels not available as
+@@ -807,7 +808,15 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ if (acs_usable_chan(adj_chan)) {
+ factor += adj_chan->interference_factor;
+ total_weight += 1;
++ } else {
++ update_best = false;
+ }
++
++ /* find the best channel in this segment */
++ if (update_best &&
++ adj_chan->interference_factor <
++ best->interference_factor)
++ best = adj_chan;
+ }
+
+ if (j != n_chans) {
+@@ -816,6 +825,18 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ continue;
+ }
+
++ /* If the AP is in the 5 GHz or 6 GHz band, lets prefer a less
++ * crowded primary channel if one was found in the segment */
++ if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
++ chan != best) {
++ wpa_printf(MSG_DEBUG,
++ "ACS: promoting channel %d over %d (less interference %Lg/%Lg)",
++ best->chan, chan->chan,
++ chan->interference_factor,
++ best->interference_factor);
++ chan = best;
++ }
++
+ /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
+ * channel interference factor. */
+ if (is_24ghz_mode(mode->mode)) {
+--
+2.18.0
+
diff --git a/autobuild_mac80211_release/package/network/services/hostapd/patches/mtk-0046-hostapd-mtk-ACS-Fix-2.4GHz-HT40-case-and-channel-swi.patch b/autobuild_mac80211_release/package/network/services/hostapd/patches/mtk-0046-hostapd-mtk-ACS-Fix-2.4GHz-HT40-case-and-channel-swi.patch
new file mode 100644
index 0000000..31e92e6
--- /dev/null
+++ b/autobuild_mac80211_release/package/network/services/hostapd/patches/mtk-0046-hostapd-mtk-ACS-Fix-2.4GHz-HT40-case-and-channel-swi.patch
@@ -0,0 +1,333 @@
+From 97b4dbb136ff86dd6ca7fac5fb4ce9356337a8bd Mon Sep 17 00:00:00 2001
+From: Evelyn Tsai <evelyn.tsai@mediatek.com>
+Date: Sat, 11 Nov 2023 11:42:59 +0800
+Subject: [PATCH] hostapd: mtk: ACS: Fix 2.4GHz HT40 case and channel switch
+ fail
+
+Issue#1. Add 2.4G HT40- support
+1. Add 2.4G HT40- support
+2. Fix issue: selected best channel is out of channels
+
+Issue#2. Fix chan_switch to usable DFS channel fail due to ACS
+
+Step and issue:
+1. Enable ACS in hostapd config;
+2. Bootup and then use hostapd_cli cmd switch channel to a DFS channel;
+3. Will do ACS again, and no work on channel specified in step 2.
+
+Root cause:
+When need do DFS-CAC, hostapd will do intf disable, then set the new
+channel into running config settings, and finally enable intf;
+In the test case, new DFS channel is set to runnint config settings, but
+another param "acs" is still 1 (enable), caused the ACS running when
+intf enabled.
+
+CR-Id: WCNCR00240772
+---
+ src/ap/acs.c | 170 +++++++++++++++++++++++++----------------------
+ src/ap/hostapd.c | 3 +
+ 2 files changed, 93 insertions(+), 80 deletions(-)
+
+diff --git a/src/ap/acs.c b/src/ap/acs.c
+index 130e135..73d2195 100644
+--- a/src/ap/acs.c
++++ b/src/ap/acs.c
+@@ -577,12 +577,6 @@ static void acs_survey_mode_interference_factor(
+ iface->conf->acs_exclude_dfs)
+ continue;
+
+- if (!is_in_chanlist(iface, chan))
+- continue;
+-
+- if (!is_in_freqlist(iface, chan))
+- continue;
+-
+ if (chan->max_tx_power < iface->conf->min_tx_power)
+ continue;
+
+@@ -712,17 +706,29 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ struct hostapd_channel_data **ideal_chan,
+ long double *ideal_factor)
+ {
+- struct hostapd_channel_data *chan, *adj_chan = NULL, *best;
++ struct hostapd_channel_data *chan, *adj_chan = NULL, *tmp_chan = NULL, *best;
+ long double factor;
+ int i, j;
+ unsigned int k;
++ int ht40_plus = 1, sec_ch_factor = 1;
++
++ if (is_24ghz_mode(mode->mode)) {
++ ht40_plus = (iface->conf->secondary_channel == -1) ? 0 : 1;
++ sec_ch_factor = (iface->conf->secondary_channel == -1) ? -1 : 1;
++ }
++
++ wpa_printf(MSG_INFO, "%s:%d, bw(%u), n_chans(%d), num_channels(%d), sec_ch(%d)",
++ __func__, __LINE__, bw, n_chans, mode->num_channels, iface->conf->secondary_channel);
+
+ for (i = 0; i < mode->num_channels; i++) {
+ double total_weight;
+ struct acs_bias *bias, tmp_bias;
+- bool update_best = true;
++ bool update_best = true, has_candidate = true;
+
+ best = chan = &mode->channels[i];
++ wpa_printf(MSG_INFO,
++ "ACS: Channel[%d] %d: interference_factor %Lg",
++ i, chan->chan, chan->interference_factor);
+
+ /* Since in the current ACS implementation the first channel is
+ * always a primary channel, skip channels not available as
+@@ -735,11 +741,12 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ iface->conf->acs_exclude_dfs)
+ continue;
+
+- if (!is_in_chanlist(iface, chan))
+- continue;
+-
+- if (!is_in_freqlist(iface, chan))
+- continue;
++ if (!is_in_chanlist(iface, chan) || !is_in_freqlist(iface, chan)) {
++ if (is_24ghz_mode(mode->mode))
++ continue;
++ else
++ has_candidate = false;
++ }
+
+ if (chan->max_tx_power < iface->conf->min_tx_power)
+ continue;
+@@ -747,7 +754,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ if (chan->flag & HOSTAPD_CHAN_INDOOR_ONLY && iface->conf->country[2] == 0x4f)
+ continue;
+
+- if (!chan_bw_allowed(chan, bw, 1, 1)) {
++ if (!chan_bw_allowed(chan, bw, ht40_plus, 1)) {
+ wpa_printf(MSG_DEBUG,
+ "ACS: Channel %d: BW %u is not supported",
+ chan->chan, bw);
+@@ -789,60 +796,76 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ }
+
+ factor = 0;
+- if (acs_usable_chan(chan))
+- factor = chan->interference_factor;
+- total_weight = 1;
++ total_weight = 0;
+
+- for (j = 1; j < n_chans; j++) {
+- adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
+- if (!adj_chan)
+- break;
+-
+- if (!chan_bw_allowed(adj_chan, bw, 1, 0)) {
+- wpa_printf(MSG_DEBUG,
+- "ACS: PRI Channel %d: secondary channel %d BW %u is not supported",
+- chan->chan, adj_chan->chan, bw);
+- break;
+- }
+-
+- if (acs_usable_chan(adj_chan)) {
+- factor += adj_chan->interference_factor;
++ if (!is_24ghz_mode(mode->mode)) {
++ /* If the AP is in the 5 GHz or 6 GHz band, lets prefer a less
++ * crowded primary channel if one was found in the segment */
++ if (acs_usable_chan(chan)) {
++ factor += chan->interference_factor;
+ total_weight += 1;
+- } else {
+- update_best = false;
+ }
+
+- /* find the best channel in this segment */
+- if (update_best &&
+- adj_chan->interference_factor <
+- best->interference_factor)
+- best = adj_chan;
+- }
++ for (j = 1; j < n_chans; j++) {
++ adj_chan = acs_find_chan(iface, chan->freq + j * 20);
++ if (!adj_chan)
++ break;
+
+- if (j != n_chans) {
+- wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
+- chan->chan);
+- continue;
+- }
++ if (!chan_bw_allowed(adj_chan, bw, 1, 0)) {
++ wpa_printf(MSG_DEBUG,
++ "ACS: PRI Channel %d: secondary channel %d BW %u is not supported",
++ chan->chan, adj_chan->chan, bw);
++ break;
++ }
+
+- /* If the AP is in the 5 GHz or 6 GHz band, lets prefer a less
+- * crowded primary channel if one was found in the segment */
+- if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
+- chan != best) {
+- wpa_printf(MSG_DEBUG,
+- "ACS: promoting channel %d over %d (less interference %Lg/%Lg)",
+- best->chan, chan->chan,
+- chan->interference_factor,
+- best->interference_factor);
+- chan = best;
+- }
++ update_best = true;
++ if (acs_usable_chan(adj_chan)) {
++ factor += adj_chan->interference_factor;
++ total_weight += 1;
++
++ if (!is_in_chanlist(iface, adj_chan) ||
++ !is_in_freqlist(iface, adj_chan))
++ update_best = false;
++ } else {
++ update_best = false;
++ }
++
++ /* find the best channel in this segment */
++ if (update_best && (!has_candidate ||
++ adj_chan->interference_factor < best->interference_factor)) {
++ best = adj_chan;
++ has_candidate = true;
++ }
++ }
+
+- /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
+- * channel interference factor. */
+- if (is_24ghz_mode(mode->mode)) {
++ if (j != n_chans || !has_candidate) {
++ wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
++ chan->chan);
++ continue;
++ }
++
++ if (chan != best) {
++ wpa_printf(MSG_INFO,
++ "ACS: promoting channel %d over %d (less interference %Lg/%Lg)",
++ best->chan, chan->chan,
++ chan->interference_factor,
++ best->interference_factor);
++ chan = best;
++ }
++ } else {
+ for (j = 0; j < n_chans; j++) {
++ /* Will set primary_channel / secondary_channel(40M case) weight to 1 */
++ tmp_chan = acs_find_chan(iface, chan->freq +
++ (j * 20) * sec_ch_factor);
++ if (tmp_chan && acs_usable_chan(tmp_chan)) {
++ factor += tmp_chan->interference_factor;
++ total_weight += 1;
++ }
++
++ /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent channel
++ interference factor, separately for primary/secondary channel. */
+ adj_chan = acs_find_chan(iface, chan->freq +
+- (j * 20) - 5);
++ ((j * 20) - 5) * sec_ch_factor);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+@@ -850,7 +873,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+- (j * 20) - 10);
++ ((j * 20) - 10) * sec_ch_factor);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_NEXT_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+@@ -858,7 +881,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+- (j * 20) + 5);
++ ((j * 20) + 5) * sec_ch_factor);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+@@ -866,7 +889,7 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+- (j * 20) + 10);
++ ((j * 20) + 10) * sec_ch_factor);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_NEXT_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+@@ -875,7 +898,8 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+ }
+ }
+
+- factor /= total_weight;
++ if (total_weight)
++ factor /= total_weight;
+
+ bias = NULL;
+ if (iface->conf->acs_chan_bias) {
+@@ -894,11 +918,11 @@ acs_find_ideal_chan_mode(struct hostapd_iface *iface,
+
+ if (bias) {
+ factor *= bias->bias;
+- wpa_printf(MSG_DEBUG,
++ wpa_printf(MSG_INFO,
+ "ACS: * channel %d: total interference = %Lg (%f bias)",
+ chan->chan, factor, bias->bias);
+ } else {
+- wpa_printf(MSG_DEBUG,
++ wpa_printf(MSG_INFO,
+ "ACS: * channel %d: total interference = %Lg",
+ chan->chan, factor);
+ }
+@@ -939,14 +963,6 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
+ goto bw_selected;
+ }
+
+- /* TODO: HT40- support */
+-
+- if (iface->conf->ieee80211n &&
+- iface->conf->secondary_channel == -1) {
+- wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
+- return NULL;
+- }
+-
+ if (iface->conf->ieee80211n &&
+ iface->conf->secondary_channel)
+ n_chans = 2;
+@@ -981,7 +997,7 @@ bw_selected:
+ }
+
+ if (ideal_chan) {
+- wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
++ wpa_printf(MSG_INFO, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
+ ideal_chan->chan, ideal_chan->freq, ideal_factor);
+ return ideal_chan;
+ }
+@@ -1169,12 +1185,6 @@ static int * acs_request_scan_add_freqs(struct hostapd_iface *iface,
+ iface->conf->acs_exclude_dfs))
+ continue;
+
+- if (!is_in_chanlist(iface, chan))
+- continue;
+-
+- if (!is_in_freqlist(iface, chan))
+- continue;
+-
+ if (chan->max_tx_power < iface->conf->min_tx_power)
+ continue;
+
+diff --git a/src/ap/hostapd.c b/src/ap/hostapd.c
+index f2eb638..250c168 100644
+--- a/src/ap/hostapd.c
++++ b/src/ap/hostapd.c
+@@ -3895,6 +3895,9 @@ hostapd_switch_channel_fallback(struct hostapd_iface *iface,
+
+ iface->freq = freq_params->freq;
+ iface->conf->channel = freq_params->channel;
++ if (iface->conf->channel != 0) /* If channel not zero, will disable acs. */
++ iface->conf->acs = 0;
++
+ iface->conf->secondary_channel = freq_params->sec_channel_offset;
+ hostapd_set_oper_centr_freq_seg0_idx(iface->conf, seg0_idx);
+ hostapd_set_oper_centr_freq_seg1_idx(iface->conf, seg1_idx);
+--
+2.18.0
+