Hi,
Recently I hit an IoT issue while connecting to an TP-LINK AP. As a station, the
connection with the AP initially succeeded, as indicated by the authentication and
association logs:
[ 528.655093] wlan0: authenticate with 16:d8:64:56:ab:5b (local address=66:81:93:de:79:d8)
[ 528.655112] wlan0: send auth to 16:d8:64:56:ab:5b (try 1/3)
[ 528.720573] wlan0: authenticate with 16:d8:64:56:ab:5b (local address=66:81:93:de:79:d8)
[ 528.720584] wlan0: send auth to 16:d8:64:56:ab:5b (try 1/3)
[ 528.790413] wlan0: authenticated
[ 528.794115] wlan0: associate with 16:d8:64:56:ab:5b (try 1/3)
[ 528.831371] wlan0: RX AssocResp from 16:d8:64:56:ab:5b (capab=0x1911 status=0 aid=1024)
[ 528.858116] wlan0: [link 0] local address 9e:c1:c3:67:13:db, AP link address
14:d8:64:4c:ab:5b
[ 528.858201] wlan0: [link 1] local address 66:81:93:de:79:d8, AP link address
14:d8:64:4c:ab:5c (assoc)
[ 528.911598] wlan0: associated
[ 528.978910] wlan0: Limiting TX power to 35 (35 - 0) dBm as advertised by 14:d8:64:4c:ab:5c
However, the connection was later disrupted:
[ 533.845338] wlan0: AP EHT information doesn't match HT/VHT/HE, disabling EHT
[ 533.845344] wlan0: [link 1] AP 14:d8:64:4c:ab:5c appears to change mode (expected EHT,
found HE) in beacon, disconnect
with some logs added:
---
+static void cfg80211_dump_chan_def(const struct cfg80211_chan_def *def)
+{
+ struct ieee80211_channel *chan = def->chan;
+ pr_info("chan: [band %u center_freq %u freq_offset %u hw_value %u flags %u
max_antenna_gain %u max_power %u max_reg_power %u beacon_found %u orig_flags %u] width %u
center_freq1 %u center_freq2 %u freq1_offset %u punctured %u\n",
+ chan->band, chan->center_freq, chan->freq_offset, chan->hw_value,
chan->flags, chan->max_antenna_gain, chan->max_power, chan->max_reg_power,
chan->beacon_found, chan->orig_flags,
+ def->width, def->center_freq1, def->center_freq2, def->freq1_offset,
def->punctured);
+}
+
static const struct cfg80211_chan_def *
_cfg80211_chandef_compatible(const struct cfg80211_chan_def *c1,
const struct cfg80211_chan_def *c2)
{
const struct cfg80211_chan_def *ret;
+ cfg80211_dump_chan_def(c1);
+ cfg80211_dump_chan_def(c2);
+
/* If they are identical, return */
---
The disconnection is caused by different 'punctured':
[ 533.845311] chan: [band 1 center_freq 5180 freq_offset 0 hw_value 36 flags 524320
max_antenna_gain 6 max_power 24 max_reg_power 24 beacon_found 1 orig_flags 0] width 3
center_freq1 5210 center_freq2 0 freq1_offset 0 punctured 0
[ 533.845322] chan: [band 1 center_freq 5180 freq_offset 0 hw_value 36 flags 524320
max_antenna_gain 6 max_power 24 max_reg_power 24 beacon_found 1 orig_flags 0] width 3
center_freq1 5210 center_freq2 0 freq1_offset 0 punctured 8
This 'punctured' is suddenly (I mean even 'EHT Operation' was not seen in previous
beacons) advertised in EHT Operation element contained in AP's beacon:
Ext Tag: EHT Operation (802.11be D3.0)
Ext Tag length: 10 (Tag len: 11)
Ext Tag Number: EHT Operation (802.11be D3.0) (106)
EHT Operation Parameters: 0x03, EHT Operation Information Present, Disabled Subchannel
Bitmap Present
.... ...1 = EHT Operation Information Present: True
.... ..1. = Disabled Subchannel Bitmap Present: True
.... .0.. = EHT Default PE Duration: False
.... 0... = Group Addressed BU Indication Limit: False
..00 .... = Group Addressed BU Indication Exponent: 0
00.. .... = Reserved: 0x0
Basic EHT-MCS And Nss Set: 0x00000011
Control: 0x02, Channel Width: 80 MHz EHT BSS bandwidth
.... .010 = Channel Width: 80 MHz EHT BSS bandwidth (2)
0000 0... = Reserved: 0x00
CCFS0: 0x0000002a
CCFS1: 0x00000000
Disabled Subchannel Bitmap: 0x0008
Which fails the check in _cfg80211_chandef_compatible(), because the chandef's are not
identical but have the same width.
Is this AP misbehaving? or is cfg80211/mac80211 not doing correctly?
I am not very familiar with Puncturing, want to hear professional opinions from your guys.
Thanks
Baochen
