Bug 175401 - iwlwifi intel 7260ac will not connect in 802.11ac
Summary: iwlwifi intel 7260ac will not connect in 802.11ac
Status: CLOSED INSUFFICIENT_DATA
Alias: None
Product: Drivers
Classification: Unclassified
Component: network-wireless (show other bugs)
Hardware: x86-64 Linux
: P1 normal
Assignee: DO NOT USE - assign "network-wireless-intel" component instead
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-10-02 13:01 UTC by john.frankish
Modified: 2017-02-16 10:03 UTC (History)
3 users (show)

See Also:
Kernel Version: 4.2.9
Subsystem:
Regression: No
Bisected commit-id:


Attachments
dmesg (42.71 KB, application/octet-stream)
2016-10-02 13:01 UTC, john.frankish
Details
wpa_supplicant log (1.79 KB, application/gzip)
2017-02-15 09:45 UTC, john.frankish
Details
wpa_supplicant-2.6 log (5.99 KB, application/gzip)
2017-02-15 11:53 UTC, john.frankish
Details
wpa_supplicant log (7.90 KB, application/gzip)
2017-02-16 07:30 UTC, john.frankish
Details

Description john.frankish 2016-10-02 13:01:14 UTC
Created attachment 240601 [details]
dmesg

intel 7260ac will not connect in 802.11ac mode - using the same hardware in the same physical location with windows 10, it does connect in 802.11ac.

iwlwifi 0000:02:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144

iwlwifi 0000:02:00.0: Direct firmware load for iwlwifi-7260-15.ucode failed with error -2
iwlwifi 0000:02:00.0: loaded firmware version 15.227938.0 op_mode iwlmvm

$ iwconfig wlan0
wlan0     IEEE 802.11abgn  ESSID:"xxxxxx"  
          Mode:Managed  Frequency:5.5 GHz  Access Point: A0:55:4F:66:D5:10   
          Bit Rate=6 Mb/s   Tx-Power=22 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=51/70  Signal level=-59 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:2   Missed beacon:0

$ iw dev wlan0 link
Connected to a0:55:4f:66:d5:10 (on wlan0)
        SSID: xxxxxx
        freq: 5500
        RX: 3713428 bytes (3012 packets)
        TX: 234657 bytes (1405 packets)
        signal: -59 dBm
        tx bitrate: 6.0 MBit/s

        bss flags:      short-slot-time
        dtim period:    2
        beacon int:     100

>netsh wlan show interfaces

There is 1 interface on the system:

    Name                   : Wireless Network Connection
    Description            : Intel(R) Dual Band Wireless-AC 7260
    GUID                   : 8f3e1d86-45d1-47eb-867a-2a072cd9a2fa
    Physical address       : a0:a8:cd:2c:3e:13
    State                  : connected
    SSID                   : xxxxxx
    BSSID                  : a0:55:4f:66:d5:10
    Network type           : Infrastructure
    Radio type             : 802.11ac
    Authentication         : WPA2-Personal
    Cipher                 : CCMP
    Connection mode        : Auto Connect
    Channel                : 100
    Receive rate (Mbps)    : 866.7
    Transmit rate (Mbps)   : 866.7
    Signal                 : 99%
    Profile                : xxxxxx

    Hosted network status  : Not started


C:\Users\J>
Comment 1 john.frankish 2016-10-04 07:31:33 UTC
I check again using crda - the previous tests were made without crda loaded - but it does not make any difference.

Under linux I cannot connect at anything greater than 6Mb/s on either 2.4GHz or 5GHz, whereas windows shows 867Mb/s (the theoretical maximum I guess) and appears to communicate at +/- 500Mb/s.

From the dmesg output it appears that connecting to the WAP forces a crda change to Germany - I am in the UAE with the locale set to US.

----------

Intel(R) Wireless WiFi driver for Linux
Copyright(c) 2003- 2015 Intel Corporation
iwlwifi 0000:02:00.0: Direct firmware load for iwlwifi-7260-15.ucode failed with error -2
iwlwifi 0000:02:00.0: Falling back to user helper
cfg80211: World regulatory domain updated:
cfg80211:  DFS Master region: unset
cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
cfg80211:   (2457000 KHz - 2482000 KHz @ 20000 KHz, 92000 KHz AUTO), (N/A, 2000 mBm), (N/A)
cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (N/A, 2000 mBm), (N/A)
cfg80211:   (5170000 KHz - 5250000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (N/A)
cfg80211:   (5250000 KHz - 5330000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (0 s)
cfg80211:   (5490000 KHz - 5730000 KHz @ 160000 KHz), (N/A, 2000 mBm), (0 s)
cfg80211:   (5735000 KHz - 5835000 KHz @ 80000 KHz), (N/A, 2000 mBm), (N/A)
cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 0 mBm), (N/A)
iwlwifi 0000:02:00.0: loaded firmware version 15.227938.0 op_mode iwlmvm
iwlwifi 0000:02:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
iwlwifi 0000:02:00.0: L1 Enabled - LTR Enabled
wlan0: authenticate with a0:55:4f:66:d5:18
wlan0: send auth to a0:55:4f:66:d5:18 (try 1/3)
wlan0: authenticated
wlan0: associate with a0:55:4f:66:d5:18 (try 1/3)
wlan0: RX AssocResp from a0:55:4f:66:d5:18 (capab=0x411 status=0 aid=4)
wlan0: associated
cfg80211: Regulatory domain changed to country: DE
cfg80211:  DFS Master region: ETSI
cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
cfg80211:   (2400000 KHz - 2483500 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
cfg80211:   (5150000 KHz - 5250000 KHz @ 80000 KHz, 200000 KHz AUTO), (N/A, 2000 mBm), (N/A)
cfg80211:   (5250000 KHz - 5350000 KHz @ 80000 KHz, 200000 KHz AUTO), (N/A, 2000 mBm), (0 s)
cfg80211:   (5470000 KHz - 5725000 KHz @ 160000 KHz), (N/A, 2698 mBm), (0 s)
cfg80211:   (5725000 KHz - 5875000 KHz @ 80000 KHz), (N/A, 1397 mBm), (N/A)
cfg80211:   (57000000 KHz - 66000000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)

$ iw reg get
global
country DE: DFS-ETSI
        (2400 - 2483 @ 40), (N/A, 20), (N/A)
        (5150 - 5250 @ 80), (N/A, 20), (N/A), NO-OUTDOOR, AUTO-BW
        (5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
        (5470 - 5725 @ 160), (N/A, 26), (0 ms), DFS
        (5725 - 5875 @ 80), (N/A, 13), (N/A)
        (57000 - 66000 @ 2160), (N/A, 40), (N/A)

$ iw dev wlan0 link
Connected to a0:55:4f:66:d5:18 (on wlan0)
        SSID: bobnet
        freq: 2462
        RX: 11879 bytes (100 packets)
        TX: 1373 bytes (9 packets)
        signal: -57 dBm
        tx bitrate: 6.0 MBit/s

        bss flags:      short-preamble short-slot-time
        dtim period:    2
        beacon int:     100
Comment 2 Luca Coelho 2016-10-11 07:23:55 UTC
Sorry for the delay in replying.  A couple of things here.

First of all, how are you checking that you're not getting the expected bitrate? The value shown in "iw dev wlan0 link" only reflects the bitrate used in the last frame sent or so.  The TX bitrate is changing all the time, to adjust to the RF environment you are in.  Additionally, management frames can only be sent a lower bitrates (e.g. 6 Mbit/s).  This problem explains why you only see 6.0 Mbit/s in the wlan0 link report.  Try to check the actual throughput with a tool like iperf or such.  Or you can try to use a sniffer to check the bitrate of more than just the last frame sent.

Second, about regulatory.  My guess is that your AP is reporting as being in Germany, thus the regulatory change after association.  This should not affect bitrates at all, but it's not a very good idea to run an AP set to the wrong country, because you may break local regulations.
Comment 3 john.frankish 2016-10-11 12:37:25 UTC
If I check two locations using iperf-3.1.3 for linux and windows on the same hardware, I get:

location 1 linux 49Mb/s windows 142Mb/s
location 2 linux 92Mb/s windows 303Mb/s

..so whilst this is better than 6Mb/s, windows is consistently finding 3x the bandwidth on the same hardware in the same location.

..which makes me think windows is using 802.11ac and linux is using 802.11a/b/g/n, but how to tell and how to force linux to use 802.11ac?

----------

iperf results from linux:

Location 1

$ iperf3 -c 192.168.1.200
Connecting to host 192.168.1.200, port 5201
[  4] local 192.168.1.102 port 54168 connected to 192.168.1.200 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec  5.28 MBytes  44.3 Mbits/sec    0    120 KBytes       
[  4]   1.00-2.00   sec  6.64 MBytes  55.7 Mbits/sec    0    189 KBytes       
[  4]   2.00-3.00   sec  5.91 MBytes  49.6 Mbits/sec    0    209 KBytes       
[  4]   3.00-4.00   sec  5.74 MBytes  48.2 Mbits/sec    0    245 KBytes       
[  4]   4.00-5.00   sec  6.52 MBytes  54.7 Mbits/sec    0    270 KBytes       
[  4]   5.00-6.00   sec  6.22 MBytes  52.2 Mbits/sec    0    283 KBytes       
[  4]   6.00-7.00   sec  5.60 MBytes  47.0 Mbits/sec    0    313 KBytes       
[  4]   7.00-8.00   sec  6.29 MBytes  52.7 Mbits/sec    0    329 KBytes       
[  4]   8.00-9.00   sec  5.52 MBytes  46.3 Mbits/sec    0    345 KBytes       
[  4]   9.00-10.00  sec  5.64 MBytes  47.3 Mbits/sec    0    413 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  59.4 MBytes  49.8 Mbits/sec    0             sender
[  4]   0.00-10.00  sec  57.9 MBytes  48.6 Mbits/sec                  receiver

Location 2

$ iperf3 -c 192.168.1.200
Connecting to host 192.168.1.200, port 5201
[  4] local 192.168.1.102 port 54198 connected to 192.168.1.200 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec  9.28 MBytes  77.8 Mbits/sec    0    141 KBytes       
[  4]   1.00-2.00   sec  11.5 MBytes  96.2 Mbits/sec    0    209 KBytes       
[  4]   2.00-3.00   sec  11.8 MBytes  98.7 Mbits/sec    0    256 KBytes       
[  4]   3.00-4.00   sec  11.3 MBytes  95.0 Mbits/sec    0    363 KBytes       
[  4]   4.00-5.00   sec  10.8 MBytes  90.9 Mbits/sec    0    444 KBytes       
[  4]   5.00-6.00   sec  10.6 MBytes  88.7 Mbits/sec    0    467 KBytes       
[  4]   6.00-7.00   sec  11.0 MBytes  92.4 Mbits/sec    0    467 KBytes       
[  4]   7.00-8.00   sec  11.1 MBytes  93.0 Mbits/sec    0    467 KBytes       
[  4]   8.00-9.00   sec  11.6 MBytes  97.6 Mbits/sec    0    467 KBytes       
[  4]   9.00-10.00  sec  11.2 MBytes  94.3 Mbits/sec    0    467 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec   110 MBytes  92.5 Mbits/sec    0             sender
[  4]   0.00-10.00  sec   109 MBytes  91.1 Mbits/sec                  receiver

iperf results from windows 10:

Location

Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. All rights reserved.

C:\WINDOWS\system32>C:\Users\J\Downloads\iperf\iperf-3.1.3-win64\iperf3 -c 192.168.1.200
Connecting to host 192.168.1.200, port 5201
[  4] local 192.168.1.102 port 49824 connected to 192.168.1.200 port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.01   sec  14.4 MBytes   120 Mbits/sec
[  4]   1.01-2.01   sec  17.9 MBytes   150 Mbits/sec
[  4]   2.01-3.00   sec  17.8 MBytes   150 Mbits/sec
[  4]   3.00-4.00   sec  16.2 MBytes   137 Mbits/sec
[  4]   4.00-5.00   sec  17.6 MBytes   148 Mbits/sec
[  4]   5.00-6.00   sec  18.2 MBytes   153 Mbits/sec
[  4]   6.00-7.00   sec  17.2 MBytes   145 Mbits/sec
[  4]   7.00-8.00   sec  16.4 MBytes   137 Mbits/sec
[  4]   8.00-9.00   sec  17.1 MBytes   144 Mbits/sec
[  4]   9.00-10.01  sec  16.8 MBytes   140 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.01  sec   170 MBytes   142 Mbits/sec                  sender
[  4]   0.00-10.01  sec   170 MBytes   142 Mbits/sec                  receiver


Location 2

[  4] local 192.168.1.102 port 49855 connected to 192.168.1.200 port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.00   sec  36.2 MBytes   303 Mbits/sec
[  4]   1.00-2.01   sec  35.2 MBytes   295 Mbits/sec
[  4]   2.01-3.00   sec  34.5 MBytes   291 Mbits/sec
[  4]   3.00-4.01   sec  37.1 MBytes   310 Mbits/sec
[  4]   4.01-5.00   sec  35.8 MBytes   301 Mbits/sec
[  4]   5.00-6.00   sec  32.5 MBytes   273 Mbits/sec
[  4]   6.00-7.00   sec  37.6 MBytes   316 Mbits/sec
[  4]   7.00-8.00   sec  37.9 MBytes   317 Mbits/sec
[  4]   8.00-9.00   sec  37.0 MBytes   311 Mbits/sec
[  4]   9.00-10.00  sec  37.5 MBytes   314 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.00  sec   361 MBytes   303 Mbits/sec                  sender
[  4]   0.00-10.00  sec   361 MBytes   303 Mbits/sec                  receiver
Comment 4 Luca Coelho 2016-11-29 07:53:33 UTC
Are you able to provide a sniffer capture of this? Just the connection and some data flow should be enough.

Also, if you could capture trace-cmd logs as described here, it would be helpful:

https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi/debugging
Comment 5 john.frankish 2016-11-30 05:13:47 UTC
Could you explain what you mean by "sniffer capture" please?
Comment 6 Luca Coelho 2016-11-30 07:35:00 UTC
By "sniffer capture" I meant that you could use wireshark (or another so-called packet analyzer tool) on a different machine that has a WiFi NIC.  You need to put its interface in monitor mode, e.g. "iw wlan0 set type monitor" and use wireshark to "sniff" on that interface.  This should give us a capture of all the WiFi packets going out in the air so we can check what is going on.  Let me know if you have a separate machine to run this and I can give you more detailed instructions.

My colleague, Emmanuel, also suggested that you could try to disable power save mode.  Windows doesn't have PS mode, so this could explain why you get better throughput there.  You can disable PS mode by loading the iwlmvm module with "power_scheme=1".
Comment 7 john.frankish 2017-02-08 10:39:59 UTC
I tried loading the iwlmvm module with "power_scheme=1", but it did not appear to change anything - how do I verify the switch was accepted?

I believe I can make a set up to monitor wlan0 with wireshark on another machine, but wouldn't I need to force iwlwifi to attempt to connect with 802.11ac - how do I do that?

At the moment, I almost always get a connection in the 2.4GHz band.
Comment 8 john.frankish 2017-02-15 07:42:55 UTC
finally - using:

"options iwlmvm power_scheme=1" in /etc/modprobe.conf
"freq_list=5240" in the network section of the wpa_supplicant conf file

..I get iperf results consistant with those I see in windows.
Comment 9 Emmanuel Grumbach 2017-02-15 07:45:18 UTC
so apparently the supplicant was preferring the 2.4GHz somehow.
Comment 10 john.frankish 2017-02-15 07:51:15 UTC
I've noticed that if I move around so that in some cases the 2.4ghz signal strength is greater than the 5ghz signal strength and in other cases it is weaker, wpa_supplicant will almost always connect to 2.4ghz no matter what.

In fact I have only seen one case (in many, many attempts) where wpa_supplicant connected to the 5ghz signal without forcing the issue in the conf file.

In contrast, windows almost always connects to the 5ghz signal.
Comment 11 Emmanuel Grumbach 2017-02-15 07:55:55 UTC
This is an interesting finding. I suggest you ask the question on the hostap mailing list [1].
If you do, please CC me :)

[1] - http://lists.infradead.org/mailman/listinfo/hostap
Comment 12 Ilan Peer 2017-02-15 09:18:09 UTC
It would be useful if you could share the wpa_supplicant log. It might help understand why one AP is preferred over the other. If you can, please run wpa_supplicant with -dd option.
Comment 13 john.frankish 2017-02-15 09:45:22 UTC
Created attachment 254765 [details]
wpa_supplicant log
Comment 14 john.frankish 2017-02-15 09:53:05 UTC
To go with the log above.

In this case the 2.4GHz signal was stronger, but it still connects to 2.4GHz if the 5GHz signal is stronger.

$ sudo iwlist wlan0 scanning | egrep 'Cell |Channel|Encryption|Quality|Last beacon|ESSID'
          Cell 01 - Address: A0:55:4F:66:D5:18
                    Channel:8
                    Frequency:2.447 GHz (Channel 8)
                    Quality=59/70  Signal level=-51 dBm  
                    Encryption key:on
                    ESSID:"box"
                    Extra: Last beacon: 86ms ago
...
          Cell 06 - Address: A0:55:4F:66:D5:10
                    Channel:48
                    Frequency:5.24 GHz (Channel 48)
                    Quality=42/70  Signal level=-68 dBm  
                    Encryption key:on
                    ESSID:"box"
                    Extra: Last beacon: 86ms ago
...
Comment 15 john.frankish 2017-02-15 11:53:41 UTC
Created attachment 254769 [details]
wpa_supplicant-2.6 log

using sudo wpa_supplicant -dd -Dnl80211 -i wlan0 -c/etc/wpa_configure.conf
Comment 16 Ilan Peer 2017-02-15 14:16:36 UTC
can you please rerun with -ddd? The sorted scan results are only printed in the highest debug level.
Comment 17 john.frankish 2017-02-16 07:30:35 UTC
Created attachment 254783 [details]
wpa_supplicant log

sudo wpa_supplicant -ddd -Dnl80211 -i wlan0 -c/etc/wpa_configure.conf
Comment 18 john.frankish 2017-02-16 07:33:15 UTC
Note that after getting the log above, I killed wpa_supplicant, forced 5GHz and restarted.

As per iperf (results at the end of the log), leaving wpa_supplicant to its own choice have a throughput of +/- 50mb/s whereas forcing 5GHz gave a throughput of +/- 200mb/s
Comment 19 Ilan Peer 2017-02-16 08:03:37 UTC
Hi,

According to the wpa_supplicant AP scoring, it would indeed seem that the 2.4GHz AP is proffered since it has better SNR (although the SNR for both is good).

a0:55:4f:66:d5:18 freq=2447 qual=0 noise=-89~ level=-49 snr=40* flags=0xb age=0 est=65000
a0:55:4f:66:d5:10 freq=5240 qual=0 noise=-92~ level=-67 snr=25 flags=0xb age=0 est=390001

Regards,

Ilan.
Comment 20 john.frankish 2017-02-16 08:19:18 UTC
The fact that I get four times the throughput without changing anything except the frequency would seem to indicate that the wpa_supplicant algorithm could use some adjustment?
Comment 21 john.frankish 2017-02-16 10:03:26 UTC
Using:

--- wpa_supplicant/scan.c.orig	2017-02-16 13:39:16.809997441 +0000
+++ wpa_supplicant/scan.c	2017-02-16 13:39:53.536663769 +0000
@@ -1738,7 +1738,7 @@
  * recommends 25 as a minimum SNR for 54 Mbps data rate. 30 is chosen here as a
  * conservative value.
  */
-#define GREAT_SNR 30
+#define GREAT_SNR 25
 
 #define IS_5GHZ(n) (n > 4000)
 
..wpa_supplicant now chooses the 5GHz connection where it previously chose 2.4GHz

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